OzVMX Forum

Clubroom => Bike Talk => Topic started by: Ken 737 on December 25, 2015, 09:12:58 pm

Title: Four stroke options
Post by: Ken 737 on December 25, 2015, 09:12:58 pm
Hi fellow VMXers,

I think my next vmx bike will be a four stroke. I.ve had a few XTs back in the day but can't imagine an XT or TT for vmx, as much as I love to see Rob Smith on his thumper. Probably can't find or afford a CCM, so what do you think?
I will never be at the front, so being competitive is not an issue, but handling is important, decent suspension too.

Cheers

Ken
Title: Re: Four stroke options
Post by: Nathan S on December 25, 2015, 09:58:14 pm
What era?

Title: Re: Four stroke options
Post by: oldyzman on December 25, 2015, 10:03:05 pm
HL copy...
Title: Re: Four stroke options
Post by: skypig on December 25, 2015, 10:31:11 pm
(http://i237.photobucket.com/albums/ff310/skypig/image.jpg13.jpg)
Yamaha motor, Kawasaki frame.
Title: Re: Four stroke options
Post by: oldyzman on December 25, 2015, 10:42:17 pm
Big move on the KLX! reminds me of my cousin on his KDX200.
Title: Re: Four stroke options
Post by: Curtis on December 25, 2015, 10:43:54 pm
What engine/frame combination is that?
Title: Re: Four stroke options
Post by: Ken 737 on December 25, 2015, 10:48:49 pm
Hi Nathan,
Pre 78 or Evo probably
Cheers
Title: Re: Four stroke options
Post by: Graham on December 25, 2015, 10:57:14 pm
Xt or tt 250 , 2 valve can be tuned on methanol to produce 32 hp, the one above is the xt 250 , 2 valve bored to take a 85mm piston with a stroked rod and is out to 420 cc estimate hp around 45-48, the klx chassis runs rings around the original xt.
Title: Re: Four stroke options
Post by: Noel on December 26, 2015, 09:18:53 am
Honda XL 500 in KLX 250


(http://i427.photobucket.com/albums/pp359/vintage_addict/20150829_VMX_Maitland/DSC09788_1024x680.jpg)
Title: Re: Four stroke options
Post by: FourstrokeForever on December 26, 2015, 10:08:50 am
^^^^^SWEET^^^^^ That's what I am planning to do with my spare KLX roller!
Title: Re: Four stroke options
Post by: Nathan S on December 26, 2015, 12:58:15 pm
KLXR500 would be my first choice.
KLXT550 would be worth investigation, though.
A C&J Honda (or replica) would be excellent, but too expensive for my tastes.

The early Husky 510 is almost certainly a better bike, but much harder to live with than the Jap options - parts prices and reliability seem to be cringe-inducing.

And without wanting to bring rule arguments into this thread, I personally would be very careful of committing to an Evo project right now, particularly a 4T hybrid...
Title: Re: Four stroke options
Post by: Oldfart on December 26, 2015, 02:06:08 pm
Nathan , why not !!! 
Title: Re: Four stroke options
Post by: Nathan S on December 26, 2015, 02:37:36 pm
While the rules remain unclear, it's likely that whatever you build could end up being illegal, less competitive or simply more expensive than it needs to be.
Title: Re: Four stroke options
Post by: TT5 Matt on December 26, 2015, 02:50:46 pm
yeah the xr500 motor has a strong gearbox and can be worked over for more power if needed but why not use the xr500A chassis it comes with and work the suspension to get it up to klx handleing after all to get the big 500 lump in the klx frame you have to add to the top tube and cradle thus increaseing the wheelbase

another choice could be a usa spec dr500 with the alloy swingarm std and long travel forks or go for a bombed out xr200A and work the suspension
Title: Re: Four stroke options
Post by: Oldfart on December 26, 2015, 03:01:02 pm
DR 500 trans is made of glass also, frames are way to heavy for
my liking
Title: Re: Four stroke options
Post by: LWC82PE on December 26, 2015, 03:04:28 pm
No too hard to find Profab/White Bros Honda swingarms either. Been quite a few around in recent months.
Title: Re: Four stroke options
Post by: sleepy on December 26, 2015, 05:21:31 pm
Nathan , why not !!!

Don't worry Stew, you'll atleast be able to ride it in 2016 when your arm is better that is. :) :) :) :) :)
Title: Re: Four stroke options
Post by: Tim754 on December 26, 2015, 09:00:45 pm
Pre75. Legal electric start and disk brake, full length comfortable seat, still plenty of stock and modified engine spares available*, more HP/ KW and torque than any stock 500cc two stroke VMXer, and ya can take a fellow dick head mate along with ya to cripple!

*This engine pictured runs 6mm overbore plus 6mm stroked crank and rods at 15 to1 comp  1046cc.... ;)

(http://i951.photobucket.com/albums/ad360/tdee754/scc.jpg) (http://s951.photobucket.com/user/tdee754/media/scc.jpg.html)
(http://i951.photobucket.com/albums/ad360/tdee754/scc1.jpg) (http://s951.photobucket.com/user/tdee754/media/scc1.jpg.html)
Title: Re: Four stroke options
Post by: Oldfart on December 26, 2015, 09:29:49 pm
All good Sleepy ..its all back together with a few trans mod hopefully it will stay together
Left  compression as is .....will see what happens.
Title: Re: Four stroke options
Post by: jimg1au on December 27, 2015, 07:51:31 am
rickman jawa 500cc just simply the best
pre 65 pre 70 pre 75 evo
all powers fourstroke
Title: Re: Four stroke options
Post by: Slakewell on December 27, 2015, 11:14:33 am
It's a year late but it's coming together, have all the parts just need a week in the shed.
(http://i1357.photobucket.com/albums/q747/Slakewell1/xr01_zpsbb5936ed.jpg)
(http://i1357.photobucket.com/albums/q747/Slakewell1/Pic_0820_010_zpsfd118003.jpg)

So it's a RM 125 T frame with 82 CR 250 forks , 79 CR 125 tank and KYB air shocks, will use CR 1980 plastics.
Only for Vinduro so I dont have to worry about Evo rules.
Title: Re: Four stroke options
Post by: Husk72 on December 27, 2015, 11:29:35 am
I remember reading somewhere that the old Honda 350 (XL ?) Super sport motors could hot up well, and went hard. Is that correct ?
Not knowing much about chairs, and big bangers Tim, that Black Wasp looks the business.
Good luck with the project Ken, which ever direction you head.


                                                                              Cheers, Mark.
Title: Re: Four stroke options
Post by: evo550 on December 27, 2015, 08:02:49 pm
(http://i118.photobucket.com/albums/o82/evo550/xt550yellow.jpg) (http://s118.photobucket.com/user/evo550/media/xt550yellow.jpg.html)

Xt550
Title: Re: Four stroke options
Post by: skypig on December 27, 2015, 08:54:38 pm
XT550 - that's very cool. :)
Title: Re: Four stroke options
Post by: evo550 on December 27, 2015, 09:10:44 pm
and another...
(http://i118.photobucket.com/albums/o82/evo550/xt550white2.jpg) (http://s118.photobucket.com/user/evo550/media/xt550white2.jpg.html)
Title: Re: Four stroke options
Post by: Ken 737 on December 27, 2015, 09:49:26 pm
Very nice Evo 550. Any for sale ????
Ken
Title: Re: Four stroke options
Post by: Rossvickicampbell on December 27, 2015, 11:23:14 pm
EVO550 - what is the rear guard on that please?
Title: Re: Four stroke options
Post by: LWC82PE on December 28, 2015, 02:24:02 am
https://www.dcvmx.com/xcart/product.php?productid=18405&cat=263&page=1
Title: Re: Four stroke options
Post by: Andrew L on December 28, 2015, 09:13:22 am
Funny how on one thread they're wingeing about franken bikes and on another where building them love it.
Title: Re: Four stroke options
Post by: Nathan S on December 28, 2015, 09:32:45 am
Funny how on one thread they're wingeing about franken bikes and on another where building them love it.

Difference is that the other FrankenBikes are historical aberrations, potentially using many major components from much later bikes.
Title: Re: Four stroke options
Post by: mboddy on December 28, 2015, 09:56:25 am
Funny how on one thread they're wingeing about franken bikes and on another where building them love it.

Difference is that the other FrankenBikes are historical aberrations, potentially using many major components from much later bikes.

So were there lots of Kawasaki and Suzuki 4 stroke motocross bikes racing back in the day?
Title: Re: Four stroke options
Post by: Hoony on December 28, 2015, 10:04:39 am
short answer - NO
Title: Re: Four stroke options
Post by: skypig on December 28, 2015, 10:40:06 am
4 strokes back in the day.
Obviously there were some.
It was certainly possible, if you desired.
During the "Thumpernats" era, there were plenty of 4 stroke MX creations.
Title: Re: Four stroke options
Post by: Momus on December 28, 2015, 11:03:29 am
Hi fellow VMXers,

I think my next vmx bike will be a four stroke. I.ve had a few XTs back in the day but can't imagine an XT or TT for vmx, as much as I love to see Rob Smith on his thumper. Probably can't find or afford a CCM, so what do you think?
I will never be at the front, so being competitive is not an issue, but handling is important, decent suspension too.

Cheers

Ken

The VCM EVO class in Victoria was one this year by Chris Conboy on a sensibly modified XL250S. The bike was plenty fast, reliable and looked easy to ride compared to the various big block 4 strokes that run in the class.
Title: Re: Four stroke options
Post by: shelpi on December 28, 2015, 12:18:36 pm
Funny how on one thread they're wingeing about franken bikes and on another where building them love it.

Difference is that the other FrankenBikes are historical aberrations, potentially using many major components from much later bikes.

So were there lots of Kawasaki and Suzuki 4 stroke motocross bikes racing back in the day?
my tt/xt500 donk in a 81 RM full floater was inspired by a Dutch team, for the 4 stroke class in 82, built mine in 83
Title: Re: Four stroke options
Post by: Rossvickicampbell on December 28, 2015, 01:57:26 pm
thank you LWC82PE  ;D
Title: Re: Four stroke options
Post by: 80-85 husky on December 28, 2015, 03:19:16 pm
the 510 is an easy one, they are about and parts are available with a lot of carry over to the later water cooled bikes.. even easier is to slot a (pick fave jap500 etc) into a 83 husky frame. 13 inches of plusho travel and plenty of room for that boat anchor engine...
Title: Re: Four stroke options
Post by: LWC82PE on December 30, 2015, 05:14:35 pm
EVO550 - what is the rear guard on that please?

Stilmotor made them as well

http://www.ebay.it/itm/PARAFANGO-POSTERIORE-STILMOTOR-TABELLE-PORTANUMERO-MOTOCROSS-DEPOCA-ARANCIO-/271556258090?hash=item3f3a03a92a:g:MUQAAOSw7ThUb41T

and

http://www.enduroklassiker.at/en/plastics-and-bodywork/2305-kotflgel-hinten.html

http://www.enduroklassiker.at/en/plastics-and-bodywork/2311-kotflgel-hinten.html

Title: Re: Four stroke options
Post by: crash n bern on January 11, 2016, 02:28:02 pm
There's a can Am Sonic on Bikepoint. That will set you apart from the herd.



http://www.bikepoint.com.au/private/SSE-AD-3219076/1982-Bombardier-500-Sonic-(Can-Am)
Title: Re: Four stroke options
Post by: Rossvickicampbell on January 11, 2016, 03:34:44 pm
thanks LW - mind you 120 Euros is getting out there!
Title: Re: Four stroke options
Post by: Ted on January 11, 2016, 08:19:35 pm
Hi fellow VMXers,

I think my next vmx bike will be a four stroke. I.ve had a few XTs back in the day but can't imagine an XT or TT for vmx, as much as I love to see Rob Smith on his thumper. Probably can't find or afford a CCM, so what do you think?
I will never be at the front, so being competitive is not an issue, but handling is important, decent suspension too.

Cheers

Ken

The VCM EVO class in Victoria was one this year by Chris Conboy on a sensibly modified XL250S. The bike was plenty fast, reliable and looked easy to ride compared to the various big block 4 strokes that run in the class.

Does VCM run 2T mx bikes in Evo?
Title: Re: Four stroke options
Post by: bigk on January 12, 2016, 08:26:54 pm
Yes Ted they do, EVO is for all, no differential between 2 of 4 stroke for the class.
K
Title: Re: Four stroke options
Post by: James Lee on April 29, 2016, 08:45:35 am
Im thinking of building a 4 stroke bike from stuff I have lying around here,an IT175 roller,just have to find a front wheel and an XT250 engine,not evo legal but Im sure it will be a fun bike.We mostly ride natural terrain on my mates property 2-3 times a week so no rules out there.
Anyone tried a 4T in an IT chassis?
Title: Re: Four stroke options
Post by: Nathan S on April 29, 2016, 10:28:43 am
Fitting a taller 4T motor will be difficult in any IT175 frame, which all have the shock over the top of the motor.
Also, most models have the chain on the RHS, to add to the hassle.
Title: Re: Four stroke options
Post by: James Lee on April 29, 2016, 07:20:59 pm
good point Nathan,drive is on the wrong side,shows how much Ive looked into it. :-[
Title: Re: Four stroke options
Post by: Tex on April 30, 2016, 09:29:10 am
I hear that there might be an interesting 4 stroke hybrid at the Beaufort Vinduro tomorrow...  ;)

Tex
Title: Re: Four stroke options
Post by: evo550 on May 01, 2016, 01:31:33 pm
1984 ATK 560
Title: Re: Four stroke options
Post by: James Lee on June 07, 2016, 07:53:14 pm
OK OK so I had planned on building a XT550 but a SP370 became available to me aswell as a RM125N rolling chassis.What would be my best choice to fit the SP engine into the RM frame or I was thinking of using the engine cradle from the SP and maybe grafting the RM subframe on and RM front end and swing arm?Thoughts,anyone here done similar?I have no experience with geometry/spring rates etc but will learn as I go but prefer to hear from anyone with experience in this field.
Title: Re: Four stroke options
Post by: TT5 Matt on June 07, 2016, 08:31:29 pm
someone on here from africa did it by making a new engine cradle and the front down tube had to be cut and moved forward. on s.aussie gumtree theres a sp370 motor in a pe175 floater frame for $1200 right now,maybe get the seller to send you some closer pics of the conversion.the dr400 motor is a better choice with more head finning and a stronger gear box along with cdi sparks or just get the whole bike and add rm suspension under it and save the head fork. ;) ;D
Title: Re: Four stroke options
Post by: LWC82PE on June 07, 2016, 08:46:27 pm
Have you read the article in VMX 2 issues ago on 'oldfarts' SP based bike? 1 limiting factor with the stock frame (and most other suzuki 'trail' bikes) is the position of the front sprocket in relationship to the swingarm pivot. It really depends on how wild you want to go with your set up as to what you end up doing though. Eg use another frame, or tone things down a bit and dont aim for 10 or 11" travel each end and instead use stock fame and settle for a little less travel but focus on ensuring what travel you have is the best quality it can be so no elcheapo shocks for example. The Profab swingarms specially built for the stock SP frame  are a little over an inch longer than stock. WB and FMF claimed up to about 9" of travel with these but i did the calculations and they were really stretching it there. It would be really, really picky with shock length/stroke to get what they were quoting. 8" is more realistic. I know someone who races a stocked framed one with 78 RM250C2 fork and he even has those slid up through the triples and front fender scrubs the tyre so technically they are too long. So choose your forks carefully or else you will need to have 4 or 5 inches sticking up above the triples and you can only do that with offet bar type too. He is in the process of fitting a DR400/500 swingarm i believe which is about another 1/2 longer than the Profabs specially made for the stock frame. Theres a few magazine articles out there on modded stock bikes and there's definitely some hard limits as to what you can do with stock frame withut major mods because there's only so much you can angle the swingarm/chain and this affects length/travel forks you can fit to keep the steering angle in the zone where you want it without cutting the frame and changing it.
Title: Re: Four stroke options
Post by: evo550 on June 07, 2016, 09:51:17 pm
When it comes to doing a four stroke for racing I'm of the belief that it's much easier to fit the MX models gear to the four stroke chassis then a four stroke motor to a MX chassis.
Title: Re: Four stroke options
Post by: Krikey on June 08, 2016, 12:37:05 am
When it comes to doing a four stroke for racing I'm of the belief that it's much easier to fit the MX models gear to the four stroke chassis then a four stroke motor to a MX chassis.

Easier no doubt but not as good a result. The MX frame will always be better for MX than a trail bike frame in my humble opinion
Title: Re: Four stroke options
Post by: Oldfart on June 08, 2016, 04:44:27 am
James ...sorting out swingarm pivot point in
Relation to rear axle and  front sprocket alignment
Is your starting point ....
The Dr 400 frame is a great donour , and will accept
Most Rm parts without too many mods
A  Rm 25o / 400  1980 frame is good also ...but you
Need to drop the cradle and extend the front down tube
As the Dr 400 motor is a tad too tall.
This brings us back to the above ...pivot point cenario
Title: Re: Four stroke options
Post by: LWC82PE on June 08, 2016, 08:27:20 am
Quote
This brings us back to the above ...pivot point cenario

Amusing, that it gets you back to where you started at with the stock frame. I really think it comes down to what you want the bike for and are you chasing trophies, which may require that little extra suspension travel. If not, i would just stick with/settle with the travel limits you are going have with the pivot point-sprocket issue, or just order one of these frame kits from GMC.

(http://i1105.photobucket.com/albums/h357/30782/hallman_zpsqzqe4zct.jpg~original)

Title: Re: Four stroke options
Post by: mick25 on June 08, 2016, 09:59:09 am
Leith and stew have hit this spot on ,
I raced a dr500 for five years just need to limit the travel 8 -9 inches to keep away from the above probs they just have such a tall gear box / front cog height .

Theres a guy James I know that was selling his Ktm 504 rotax engine 1983 model bike ,I think
It was on gum tree a while back I don't think he sold it ? He did want a bit for it around 6k but they are rear and its up there as being the top four beast of this era .
There's No work to be done to it , it won every race he put it in but he is a gun rider aswell

I would buy it if I had the funds .
Title: Re: Four stroke options
Post by: evo550 on June 08, 2016, 06:35:25 pm
When it comes to doing a four stroke for racing I'm of the belief that it's much easier to fit the MX models gear to the four stroke chassis then a four stroke motor to a MX chassis.

Easier no doubt but not as good a result. The MX frame will always be better for MX than a trail bike frame in my humble opinion

Only while it is fitted with the original motor, take out the light weight, compact two stroke and fit a tall, huge lump of lead and the whole attitude of the bike changes...and not for the better.
Title: Re: Four stroke options
Post by: LWC82PE on June 08, 2016, 06:45:33 pm
That's a good point. I want to see someone buy one of GMC's frames and build one like the above photo.

There is a good article in Dirt Bike by Rick Seiman where they modded a 370.
Found the one i was thinking of here

http://forum.ozvmx.com/index.php?topic=943.75
Title: Re: Four stroke options
Post by: Oldfart on June 08, 2016, 09:03:26 pm
The back of that bike looks wierd, plus the air filter looks like an after thought .....
Title: Re: Four stroke options
Post by: LWC82PE on June 08, 2016, 09:10:48 pm
I agree with the filter, needs an air box. Rear fender looks a bit short.
Title: Re: Four stroke options
Post by: Oldfart on June 08, 2016, 09:13:44 pm
My thoughts are the same as yours ...
Read article  ....last paragraph  sums it up well
Title: Re: Four stroke options
Post by: FourstrokeForever on June 09, 2016, 02:05:34 pm
When it comes to doing a four stroke for racing I'm of the belief that it's much easier to fit the MX models gear to the four stroke chassis then a four stroke motor to a MX chassis.

Easier no doubt but not as good a result. The MX frame will always be better for MX than a trail bike frame in my humble opinion

Only while it is fitted with the original motor, take out the light weight, compact two stroke and fit a tall, huge lump of lead and the whole attitude of the bike changes...and not for the better.

I agree, sticking a big thumper motor into a light weight 2 stroke chassis will change how the once great handling MXer behaves. Weight distribution is a big issue with most 2 strokes having a front biased weight balance and the motor generally higher in the frame than a 4st. The problem comes when trying to keep the counter shaft as centre and as close as possible in relation to the swing arm pivot when fitting a fourstroke into a 2st MX frame.

It is much easier to use the original "trail bike" frame and modify it with MX geometry (rake, trail, offset and wheelbase) and firmer suspension with more travel. All the parts make up the sum of the machine so you need to start with the parts you intend using before you start chopping and changing the frame. Bolt on the new front end and swingarm with wheels and then start measuring.
Title: Re: Four stroke options
Post by: LWC82PE on June 09, 2016, 05:20:26 pm
It is interesting that even White Bros thought that the stock Yam frame was good enough and you don't need a 'HL' type frame

(http://i1105.photobucket.com/albums/h357/30782/white%20bros%20yam_zpsm8km0j6j.jpg~original)
Title: Re: Four stroke options
Post by: TT5 Matt on June 09, 2016, 06:00:01 pm
theres alot of places on a 500 thumper you can save weight if you want to go to the trouble of machineing up alloy replacement components or fit yz parts
rear axle  factory drilled out yz400
swingarm pivit bolt   factory drilled out yz400
all axle spacers   machined alloy
oil return hose fitting/plate    alloy
yz400 cdi ignition   good for lots of revs
yz400 clutch
WP cam tensioner adjuster
drilled countershaft spocket
swiss chese drilled out brake shoes
drilled out brake arms and cams
and many more places if your keen to save a gram or 10
is it worth all the effort? nar still a heavy old dinasor just buy a big bore 2t of your brand choice ;) ;D ;D ;D
Title: Re: Four stroke options
Post by: LWC82PE on June 09, 2016, 06:51:16 pm
So the axle is 17mm and drilled out, what size is the hole in the middle?
Title: Re: Four stroke options
Post by: TT5 Matt on June 09, 2016, 07:11:47 pm
from memory the rear axle had a 7mm hole and was off of a yz400d, the much modded tt500d i got from dave basham and the frame was modded by a dude who worked for a pommey frame builder and the back shock mounts/frame tubes were a copy of a rm125s which gave it 8.5 inches of travel,it worked really well compared to the stock rear suspension which might be why ive got 5 herniated back disc right now :( :'(
Title: Re: Four stroke options
Post by: GMC on June 09, 2016, 07:39:24 pm
It is interesting that even White Bros thought that the stock Yam frame was good enough and you don't need a 'HL' type frame

I think they would have been more about selling products for small improvements, whether the stock frame was good enough or not I doubt would have come into it.

Forgive me if this sounds like a sales pitch but one thing about the HL vs TT frame is that the HL changes the whole ergonomics of the bike, width of set rails, riding position etc, there's more to it than just suspension changes. Of course all these things can be changed and it depends what frame (XR, DR or whatever) your modifying from as well. It comes down to what you want to achieve and how much work your willing to put in.

Title: Re: Four stroke options
Post by: Nathan S on June 09, 2016, 08:09:20 pm
I've got a DR250F here - you know, the "competition" model with an alloy swingarm and all that...

It's built like a bloody Sherman tank. Ignoring the considerable heft of the motor, there's heaps of excess weight in the thing - stuff like minor frame rails that are double the diameter of any halfway decent enduro bike, brackets onto brackets onto brackets, and lots of steel where an MXer would use alloy.
Plus the japs were all obsessed with too-short swingarms on their '80s four strokes. Presumably this is so the gutless 4Ts felt like they had some grunt, but it makes them all handle weird. (Notably, the twinshock KLX seems to be the exception to this - and it's the one with the greatest reputation for being gutless. I wonder if the sensible swingarm is at least partly responsible for this).

Add in shit shock absorbers, shit ergos, steel tanks, lousy forks/shocks and all the rest, and I can see the appeal in fitting the motor into something else.
Title: Re: Four stroke options
Post by: LWC82PE on June 09, 2016, 08:28:53 pm
Good point GMC. You know when i posted that page above i actually had thought that WB's comments were also about 'selling their product'
Title: Re: Four stroke options
Post by: GMC on June 09, 2016, 08:44:07 pm
(Notably, the twinshock KLX seems to be the exception to this - and it's the one with the greatest reputation for being gutless. I wonder if the sensible swingarm is at least partly responsible for this).

One thing about the KLX is that it was somewhat based on the 79 KX 125 with the trailbike KL motor so it started life with 'MX ergonomics'
Pity Kawaskai didn't run with this theme during the following years.
Honda's XR range wasn't too bad but the XR motor in a CR frame I'm sure would also have been very popular


As has been said previously, the swingarm pivot position is the important thing to design around but most early 4 stroke engines didn't have the swingarm pivot through the motor but by the early 80's most 2 strokes did so not only do you need to keep the countershaft sprocket close to the pivot you also need to keep the height in mind.
Title: Re: Four stroke options
Post by: Nathan S on June 09, 2016, 09:27:40 pm
xl59's XR200 powered RM125(C?) is a fantastic thing. I like XR200s, but the yellow one blows them away. It wouldn't have cost them any more to build these than what they did build...
Title: Re: Four stroke options
Post by: 80-85 husky on June 09, 2016, 09:31:03 pm
ol mate had a 350 xl shoehorned into a monty cappra (VB?) frame... I think and the whole swingarm pivot issue came into play just after landing from the first jump he tackled.. the chain doubled up into the countershaft sprocket and she stopped suddenly! :o

a lot more cutting and welding took place after that
Title: Re: Four stroke options
Post by: HeavenVMX on June 10, 2016, 11:59:35 am
ol mate had a 350 xl shoehorned into a monty cappra (VB?) frame... I think and the whole swingarm pivot issue came into play just after landing from the first jump he tackled.. the chain doubled up into the countershaft sprocket and she stopped suddenly! :o

a lot more cutting and welding took place after that
My personal opinion only not the clubs but...

That is sacrilege and blasphemy. I really don't think it would be taking it to far to say that taking a f&%kin XL350 engine and jamming it into and thus destroying a relatively rare Spanish bike is a crime against humanity.

A bit like taking a YZ250B roller and hacking it up to jam an '73 XL250 engine in it or butchering a TZ350 road racer roller to jam a CB350 engine into it. Bloody hell even if you hate Montesa bikes you must see that is just wrong FFS.
Title: Re: Four stroke options
Post by: TT5 Matt on June 10, 2016, 01:29:26 pm
so is it "wrong" to do a engine swap if the frame and other different parts of all different brands of bikes if they all came from the wreckers?after all wreckers only keep frames/forks/swingers for so long and then sell them for scrap which then goes to china?and if you blew your monty gearbox and the parts were no longer available new you wouldnt buy a 2nd hand box knowing you'd help kill off another monty so yours could live again?lets face it not all bikes can be saved as the high costs and availability of new parts wont allow it, sometimes its way cheaper to buy a 3yo modern then rebuild a 35yo bike even if you do everything yourself and just buy parts/paint. ive just done a costing on a ts185 that im getting off the wrecker here who's closing down soon,its complete minus wheels/top end/carb and airbox for $50,ive known him for 40yrs hence the cheap price but to get it up to scratch ill tip another 6 or 700 dollars into it and ive got alot of the bits needed even then it will be rebuild just to make it a reliable bike for farm work and to go to the nestest town to get basic supplies to save putting my good xh van on dirt which i hate ;)
Title: Re: Four stroke options
Post by: Nathan S on June 10, 2016, 01:58:41 pm
There was a time when the Monty was just a shitty old dirt bike with a blown up motor.
Title: Re: Four stroke options
Post by: HeavenVMX on June 10, 2016, 02:26:59 pm
so is it "wrong" to do a engine swap if the frame and other different parts of all different brands of bikes if they all came from the wreckers?after all wreckers only keep frames/forks/swingers for so long and then sell them for scrap which then goes to china?and if you blew your monty gearbox and the parts were no longer available new you wouldnt buy a 2nd hand box knowing you'd help kill off another monty so yours could live again?lets face it not all bikes can be saved as the high costs and availability of new parts wont allow it, sometimes its way cheaper to buy a 3yo modern then rebuild a 35yo bike even if you do everything yourself and just buy parts/paint. ive just done a costing on a ts185 that im getting off the wrecker here who's closing down soon,its complete minus wheels/top end/carb and airbox for $50,ive known him for 40yrs hence the cheap price but to get it up to scratch ill tip another 6 or 700 dollars into it and ive got alot of the bits needed even then it will be rebuild just to make it a reliable bike for farm work and to go to the nestest town to get basic supplies to save putting my good xh van on dirt which i hate ;)

There were around 1900 VB Montesa 250(1500)/360(400) made in total how many TS185s umm a 1000000, not the same. The VB frame could have been reunited with a Montesa engine as parts are more plentiful than many think even NOS cranks, cases, cylinders etc etc. The point is destroying a rare bike to make a POS is not a good thing. That is my opinion and obviously not yours which is totally OK.

Give me the XH van because I wouldn't buy it. I'll chop it, slamin on the ground and shuv a Chevy V8 in it, that sounds sweet or alternatively use it for a smash up derby as is. The XH van was way more plentiful than VB Monties I would think, but has no real value to me. I am however very pleased that you value it so highly, enjoy it so much and preserve it lovingly. That shows that you know what I am getting at, umm unless you have already put a Chev or a Nissan/Holden Turbo 6cl engine in it :P

Nathan almost all of our bikes start as shitty old dirt bikes as you know. But that is all relative I guess.

As I said this is my opinion not the clubs so will not respond any more.
Title: Re: Four stroke options
Post by: James Lee on June 10, 2016, 03:54:12 pm
I have a few questions,had a look at the SP and RM today and it looks like the rm swing arm will go right on the SP.Im not sure if this is my best option,I would need to make a spacer for it or I was thinking of lenthening the SP swing arm and running some flat plate stood up underneath.Any advice which way to go?The RM one would save allot of weight.Or should I find a DR alloy one as previously mentioned by LWC82PE.
Looks like the RM front end will fit straight on too,not sure if the bars will clear when I drop the forks through the clamps.LWC82PE do you think the 125 forks would be more suited that the rm250 forks?
Id like to work with what I have here as I have other bikes I need to spend money on.Im happy to buy new shocks or would rather get the RM ones rebuilt if they could work?
Im just after a VMX bike that I will enjoy riding and looking at knowing I built it.Im not worried about coming last but dont plan on it either.
Title: Re: Four stroke options
Post by: reg on June 10, 2016, 04:38:35 pm
https://scontent-lax3-1.xx.fbcdn.net/v/t1.0-9/12814294_225955714416350_1783444557190330312_n.jpg?oh=d519d0a9ac3591c721d27b09d234ed72&oe=57D7B4A0
Title: Re: Four stroke options
Post by: evo550 on June 10, 2016, 05:05:42 pm
Its interesting that people spend a fortune to try and get acfourstroke 10 kg lighter, when the rider is the one contributing to the load, imaging how well the four stroke would handle and the suspension would work if the rider lost 30 kg.....just sayin' :)
Title: Re: Four stroke options
Post by: mick25 on June 10, 2016, 05:27:26 pm
Its interesting that people spend a fortune to try and get acfourstroke 10 kg lighter, when the rider is the one contributing to the load, imaging how well the four stroke would handle and the suspension would work if the rider lost 30 kg.....just sayin' :)
Very good point some forget about there own weight  ;D
I for one have been the same racing weight since high school 79kg
So I'm trying to save weight on the bike project I'm doing now .
Title: Re: Four stroke options
Post by: LWC82PE on June 10, 2016, 05:29:58 pm
You will need to be specific when talking about what model RM parts you are considering.
The stock triple clamps are 25mm offset
All 76-78 RM clamps and 78/79 PE clamps are 30mm offset and are a straight bolt on. 76/77 RM250/370 top clamp is 35mm but lower is 36mm. 78/79 PE  77 RM125B and 78 RM250 clamps are the same but 36mm top and bottom.
78 RM125, RM400 and RM250C2 have offset rubber mounted bar mounts and will allow forks to be slid up. If you dont like the rubber mounts, replace the rubber with solid alloy replacements the same shape as the rubbers.

The alloy DR500, steel DR400 and DR500 and SP500 swingarms are all the same dimensionally apart from thickness of various parts on the alloy one is greater eg where the axle goes through. The steel ones are pretty easy to get and cheap. They are box section type. Alloy ones can be hard to find and a little pricey. It really depends on your specific set up as to what will work but there is provision the shorten any of those swingarms by about 12mm by machining the slots more forward and custom making some longer adjusters.  The SP used different swingarm pivot bolt sizes from 78-79 from memory. Some 14 and some 16mm? Basically any other RM/PE swingarm can be made to fit but some are more 'bolt on' than others. Alloy 78 RM 250/400 swingarms can be hard to find in good condition and are prone to cracking and wearing out in the pivot area, which is an area that suzuki designed a bit 'light' The Profab built swingarms i have are a lot beefier in this area.
Title: Re: Four stroke options
Post by: mick25 on June 10, 2016, 05:30:12 pm
I have a few questions,had a look at the SP and RM today and it looks like the rm swing arm will go right on the SP.Im not sure if this is my best option,I would need to make a spacer for it or I was thinking of lenthening the SP swing arm and running some flat plate stood up underneath.Any advice which way to go?The RM one would save allot of weight.Or should I find a DR alloy one as previously mentioned by LWC82PE.
Looks like the RM front end will fit straight on too,not sure if the bars will clear when I drop the forks through the clamps.LWC82PE do you think the 125 forks would be more suited that the rm250 forks?
Id like to work with what I have here as I have other bikes I need to spend money on.Im happy to buy new shocks or would rather get the RM ones rebuilt if they could work?
Im just after a VMX bike that I will enjoy riding and looking at knowing I built it.Im not worried about coming last but dont plan on it either.
They do have weak gear dogs on 3rd I broke one and my spare gear box I got for spares had the same gear broken , oldfart had the same probs on his latest sp project .
Title: Re: Four stroke options
Post by: James Lee on June 10, 2016, 05:30:20 pm
The RM I have here is a 1979 125.I got the SP running today and its sounds good but will test tomorrow for any gearbox issues.
Title: Re: Four stroke options
Post by: mick25 on June 10, 2016, 05:35:15 pm
I used to try and do a poo and a wee before BMX racing.

It all helps James  ;D
Title: Re: Four stroke options
Post by: James Lee on June 10, 2016, 05:41:45 pm
I edited that,you caught me out lol.
Title: Re: Four stroke options
Post by: mick25 on June 10, 2016, 05:43:39 pm
When I first got my dr500 it had a broken gear dog and I didn't notice it when I rode it around the paddock , but when I gave it the first oil change the broken dog fell out the sump  :'(
So I rebuilt the whole bottom end gears etc then five years later while changing the oil a broken dog was stuck inside my magnetic sump  :'(
So then I checked my spare gear box that I got from the wreckers and the same gear dog was broken in there to .
I know the dr500 and dr400 had the same part number for third gear and think the sp are the same .
and third gear is the gear most used on the track .
Title: Re: Four stroke options
Post by: mick25 on June 10, 2016, 05:45:47 pm
I edited that,you caught me out lol.
I noticed it gone ? Had me stuffed for a second , then I throught I was to fast for ya  :o
Title: Re: Four stroke options
Post by: LWC82PE on June 10, 2016, 06:16:44 pm
The 79 RM forks are 38mm and the steering stops are different. I am not so sure they will work with the frame stops without some additional mods. Stems are longer too. All the ones i suggested are bolt on's, but if you want 38mm then i guess you gotta go with 79/80 stuff then. The 38mm forks are longer than the 78 36mm forks too. I would carefully consider fork length thats for sure. Its not just a matter of chucking the extra length up out the top triple clamp which will reduce the gap you have here when full bottom.
Here are RM370 forkss you can see there is no way these can be slid up anymore. They only have a 22mm gap as standard here between slider and base of triple. This is what you need to check out, if intending to slide the forks out the clamps to reduce length.
(http://i1105.photobucket.com/albums/h357/30782/bottomed%20out%20spacing2_zpsposj3xs2.jpg~original)

 Consider the how long the stock forks are from axle hole to top of the chrome and then look at what ones you want to use. The issue is, if you go a lot longer in front and at the rear it does raise the center of gravity and ride height a lot. The bikes that these long forks may come from have all this factored in and the engine cradles sit down lower. As soon as you get into this project you will quickly learn how one thing effects another and you will need to do a lot of measuring, experimentation, trial fitting of parts etc. It can become very time consuming if you really want it to work out well. My advice is don't go to extremes with the mods and take your time with it. I would be looking for a set of forks in the 9 inch travel range roughly around 840-870mm long. The previous mentioned issues of sprocket/pivot location and distance between top shock mounts and swingarm pivot are going to limit what you can do with the front anyway. Sprocket sizes also affect things. Larger ones will give you a bit more breathing space at the buffer area but do they give you the ratio you are needing...... decisions,decisions. I hope you like spending hours in the shed :)
Title: Re: Four stroke options
Post by: yamaico on June 10, 2016, 09:33:13 pm
Its interesting that people spend a fortune to try and get acfourstroke 10 kg lighter, when the rider is the one contributing to the load, imaging how well the four stroke would handle and the suspension would work if the rider lost 30 kg.....just sayin' :)
It's all about reducing the unsprung weight...
Title: Re: Four stroke options
Post by: Tony.Brown on June 10, 2016, 09:47:06 pm
Its interesting that people spend a fortune to try and get acfourstroke 10 kg lighter, when the rider is the one contributing to the load, imaging how well the four stroke would handle and the suspension would work if the rider lost 30 kg.....just sayin' :)
It's all about reducing the unsprung weight...

Dead right Pete!
Title: Re: Four stroke options
Post by: James Lee on June 11, 2016, 07:13:55 am
At 104KG Im at my lightest,anything under 100kg and I feel like I lose some strength,so my poor bikes have to lag me around the track.
Im having a different idea with the RM chassis now,I have a fast little XT250 engine here,would this be a better choice?
Im happy to leave the SP in relatively standard form and fit the best suited forks and best shocks I can get on it and mod or fit a longer swing arm.
That way I can use the RM and end up with 2 bikes instead of one.
I have the shed to myself this weekend so will test fit some parts and see what I come up with.
GMC do you make extended bolt on swing arms for the SP?
Title: Re: Four stroke options
Post by: FourstrokeForever on June 11, 2016, 10:45:18 am
At 104KG Im at my lightest,anything under 100kg and I feel like I lose some strength,so my poor bikes have to lag me around the track.
Im having a different idea with the RM chassis now,I have a fast little XT250 engine here,would this be a better choice?
Im happy to leave the SP in relatively standard form and fit the best suited forks and best shocks I can get on it and mod or fit a longer swing arm.
That way I can use the RM and end up with 2 bikes instead of one.
I have the shed to myself this weekend so will test fit some parts and see what I come up with.
GMC do you make extended bolt on swing arms for the SP?

I'm with you in the weight department James.....My bikes have to work to carry my considerable body around  :D

If it were me with a fast XT250 motor lying around, I would put it in the RM frame. The XT motor is lighter and has smaller external dimensions than the SP and will probably fit in without too much drama.
Failing that, If you decide not use the XT motor, I'd be interested in buying it from you to fit into my restored KLX250 frame rather than trying to extract some more neddies from the fragile KLX motor!
Title: Re: Four stroke options
Post by: evo550 on June 11, 2016, 11:01:14 am
Its interesting that people spend a fortune to try and get acfourstroke 10 kg lighter, when the rider is the one contributing to the load, imaging how well the four stroke would handle and the suspension would work if the rider lost 30 kg.....just sayin' :)
It's all about reducing the unsprung weight...

Dead right Pete!

What about lowering the center of gravity.....:)
Title: Re: Four stroke options
Post by: James Lee on June 11, 2016, 12:56:17 pm
I probably over exaggerated on the XT engine I have,its stock apart from a good exhaust with alloy muffler,I have 5 running XTs and this one is way faster that the rest,I hated XTs till I got this one.
Anyway the xt engine wont fit unless I cut away the mount tube closest to the airbox and the coil tube and may have to lean the front main tube forward or,
Cut the lower rails out and make the engine part of the structure like an XT.,would that mean the engine would bottom out before full suspension compression and cause some mischief?
Im having a hard time cutting into the RM frame,its a really nice bike for whats there.I trial fitted a late DT175 to it and looked good until I saw it was a center port and wouldnt be able to get an exhaust on it.
Would love the XT engine in it,just scared to dive in with the cutting disk.
Title: Re: Four stroke options
Post by: HeavenVMX on June 11, 2016, 01:26:47 pm
What about an RM engine it will probably an easy fit ::)
Title: Re: Four stroke options
Post by: James Lee on June 11, 2016, 02:11:23 pm
If you had or knew of one at a reasonable price Id prefer to go that way,Id need electrics and pipe.Im just trying to build stuff with what I have here.
Title: Re: Four stroke options
Post by: Tomas on June 11, 2016, 02:15:18 pm
Agree HavenVMX. 79 RM 125 are great looking bikes.One of the best Suzuki's rm 125 ever made. Here is motor for your RM 125 frame http://forum.ozvmx.com/index.php?topic=40442.0  I just dont understand why would you want to waste time on puting 4 stroke engine in it that is heavier, does not fit, does not have that much horsepower and is not a Suzuki engine after all. You can probably sell the rolling frame to someone who will apreciated it as it is rather than butcher it with angle grinder.
Title: Re: Four stroke options
Post by: James Lee on June 11, 2016, 02:39:12 pm
At the end of the day this thread is called 4 stroke options,some sort of contribution would be more appreciated than hard opinions of wrong and right of other peoples property,usually 2 stroke biased.But thankyou,you have given me the motivation to go back to the shed and build something out of my $200 rolling frame purchase.will be a 4 stroke too sorry.
Title: Re: Four stroke options
Post by: FourstrokeForever on June 11, 2016, 06:39:04 pm
Go for it James. It is yours after all, and you will have something that no one else has.

Why not remove the front and rear springs and bottom the bike out to find out how much, if any ground clearance you have to play with?
I'd be very reluctant to mess with the front downtube and would rather keep the motor as far back in the frame as possible.
In saying that, I'd still be tempted to use the SP main frame and give it the MX treatment by narrowing the rear loop to fit a MX seat and fuel tank.
Anything is possible with a whole heap of parts and some imagination mixed with determination.

Funny thing about how hybrids divide opinions. When oldfart on here built a hybrid out of an RM, no one whinged and moaned about what is the supposed right and wrong thing to do with an old bike. The build even made the cover of VMX magazine!
Title: Re: Four stroke options
Post by: TT5 Matt on June 12, 2016, 11:35:55 am
ive seen a xr200 motor in a rm125n or maybe t model which no cutting and shutting of the std rm engine mounts/engine cradle, it was mocked up to be a HL. the only bad thing i could see about it was the engine was tilted back to get the countershaft spocket in the right position and youd have to run the oil level on the drip stick higher and youd have the rejig the inlet manifold for the correct factory angle
Title: Re: Four stroke options
Post by: LWC82PE on June 12, 2016, 11:58:15 am
Yeah i have seen that bike too. Not sure what forum it was on though. Maybe Thumper Talk?
Title: Re: Four stroke options
Post by: oz555ktm on June 12, 2016, 04:20:40 pm
(http://i1063.photobucket.com/albums/t512/oz555ktm/p%20mark%202.jpg) (http://s1063.photobucket.com/user/oz555ktm/media/p%20mark%202.jpg.html)

(http://i1063.photobucket.com/albums/t512/oz555ktm/p%20mark%201_1.jpg) (http://s1063.photobucket.com/user/oz555ktm/media/p%20mark%201_1.jpg.html)

(http://i1063.photobucket.com/albums/t512/oz555ktm/p%20greg%201.jpg) (http://s1063.photobucket.com/user/oz555ktm/media/p%20greg%201.jpg.html)

(http://i1063.photobucket.com/albums/t512/oz555ktm/GOPR0028_zps92afb11c.jpg) (http://s1063.photobucket.com/user/oz555ktm/media/GOPR0028_zps92afb11c.jpg.html)

photos taken of Bikes at  Vinduro

I dont have the Photo of the Yamaha TT250cc in a 1980  Husky frame

and a there bloke in the process of  is putting a Honda XR 200cc in a KTM 1984 125 frame now I think He is Bloody MAD why Cut up a KTM  :'( :'( :-[
But I can understand  wants something that Handles . and lite ..
Title: Re: Four stroke options
Post by: Sorelegs11 on June 12, 2016, 08:09:03 pm
I had an RM S with ahonda 123 with all the bells and whistles that were availiable in 1979, regoed and all.
From memory I paid 500 and rode it for a year and got the cash back, great little rig.
 Put together by a bloke by the name of Paul Burns from Hamilton South.
Title: Re: Four stroke options
Post by: James Lee on June 12, 2016, 08:28:30 pm
The Rm with the alloy wheels looks really good,I really like it apart from the head light.
Title: Re: Four stroke options
Post by: TT5 Matt on June 12, 2016, 09:02:44 pm
brentj had the xr200 powered ktm, all dump shop finds
Title: Re: Four stroke options
Post by: oz555ktm on June 12, 2016, 09:31:24 pm
(http://i1063.photobucket.com/albums/t512/oz555ktm/p%20mark%201_1.jpg) (http://s1063.photobucket.com/user/oz555ktm/media/p%20mark%201_1.jpg.html)

Want to see this Bike and hear it Click on the Youtube link  you will see it and Hear it in the bush at the start
and that the End it will Roar past .


 
                      https://youtu.be/aceGGj3M6xs

Title: Re: Four stroke options
Post by: oz555ktm on June 12, 2016, 09:55:20 pm

 Hear is a photo of that Husky/Yamaha

You get a bit of a  look

(http://i1063.photobucket.com/albums/t512/oz555ktm/Huskt%20TT%202.png) (http://s1063.photobucket.com/user/oz555ktm/media/Huskt%20TT%202.png.html)
Title: Re: Four stroke options
Post by: shelpi on June 13, 2016, 10:57:15 am
really like the RMXR200's but for the petrol tanks look weird on the angle
and the Kwaka looks the goods
I have a couple of XR200's 1x twin shock and 1x pro link 1982 got a real soft spot for em
Title: Re: Four stroke options
Post by: ola_martin on June 13, 2016, 05:44:19 pm
Cool?
(http://i1222.photobucket.com/albums/dd485/ola_martin/Mobile%20Uploads/image_zps8kfuln34.jpg) (http://s1222.photobucket.com/user/ola_martin/media/Mobile%20Uploads/image_zps8kfuln34.jpg.html)
Title: Re: Four stroke options
Post by: TT5 Matt on June 14, 2016, 12:09:14 am
i could be wrong but it looks like a SP in stock frame with longer shocks and forks?dr400's are a better base if you can find a cheap frame and swingarm
Title: Re: Four stroke options
Post by: James Lee on June 14, 2016, 08:06:07 am
Cool?
(http://i1222.photobucket.com/albums/dd485/ola_martin/Mobile%20Uploads/image_zps8kfuln34.jpg) (http://s1222.photobucket.com/user/ola_martin/media/Mobile%20Uploads/image_zps8kfuln34.jpg.html)
That is exactly what Id like to end up with from my SP.Tell me more Ola?Stock swing arm?What length shocks and what forks?Assuming it is your bike?
Title: Re: Four stroke options
Post by: James Lee on June 14, 2016, 08:11:43 am
Those side panels have me intrigued and look great.
Title: Re: Four stroke options
Post by: LWC82PE on June 14, 2016, 08:54:27 am
Forks look like 38mm RM units to me because of the pinched axle clamp, probably shortened/restricted a bit too. I have got an article somewhere that says beyond a certain shock length with stock swingarm, you need to cut off the brake cable lug on the  frame or else the swingarm hits it. Protec were one of the very first to hit the market with their version of an alloy swingarm for the 370 and each side was parallel, but some months later when White Bros gave their design to Profab they went one better and put a bend/kink in the right side which enables the swingarm to clear the frame so you dont have to mod the frame, plus they had the mount for the brake cable guide and the Protec does not. .Totally bare WB arm weighs 2339g and Protec is 2657g with bronze bushes still fitted. FMF/Al Baker supposedly offered a banana option too but i have never seen one.
Title: Re: Four stroke options
Post by: FourstrokeForever on June 14, 2016, 12:30:35 pm
Now that looks the goods! Be great to get some more detail pics/info on it.
Title: Re: Four stroke options
Post by: shelpi on June 14, 2016, 02:15:53 pm
Grate bit of kit, damn you Suzuki why the glass box
Title: Re: Four stroke options
Post by: ola_martin on June 14, 2016, 03:02:54 pm
Just a photo of a bike with stock frame, I think, don't know more about it.

Here's mine:

(http://i1222.photobucket.com/albums/dd485/ola_martin/CurtisSuzuki1_zps7704bc0f.jpg) (http://s1222.photobucket.com/user/ola_martin/media/CurtisSuzuki1_zps7704bc0f.jpg.html)
Title: Re: Four stroke options
Post by: Tony.Brown on June 14, 2016, 03:09:40 pm
I think just got a chubby!
Title: Re: Four stroke options
Post by: Oldfart on June 14, 2016, 03:56:45 pm
Dr in a Husky frame
Title: Re: Four stroke options
Post by: shelpi on June 15, 2016, 10:33:56 am
Luv it
Title: Re: Four stroke options
Post by: skypig on June 15, 2016, 11:06:02 am
That's Tidy!
(I'm concour with the chubby inducing comment.)
Title: Re: Four stroke options
Post by: James Lee on June 16, 2016, 09:49:52 am
Thats the kind of bike dreams are made of.
My SP370 is coming along nicely,I had some 35mm forks here that were sold to me as RM but the front hub had a speedo drive so Im guessing they are PE,they gave about 40-50mm more travel,I fitted the RM125 shocks by swapping the eyelets but they bottom out on the body early.Im thinking if I move the top shock mount up higher it may solve the problem.
At the moment my swing arm is hitting the cable holder for the rear brake but the rear does seem a bit too high so I dont mind loosing some ride height.
As far as suspension goes,what part of the bike should bottom out first when your setting one up like this?The RM125 79 seemed to bottom the frame out when the springs were removed so Im guessing the frame?
Im hoping to test ride tomorrow.
Title: Re: Four stroke options
Post by: FourstrokeForever on June 16, 2016, 11:18:31 am
Seems like you're hard at it James. Nearly ready for a test ride already!

What swing arm are you using? If you move the top shock mounts, chances are that someone will complain if you use the bike for a national competition.

To get the ride height you want.....remove the shocks and then the shock springs. Set the bike on an adjustable jack with the height dictated by your known ground clearance measurement. (While speaking of ground clearance, it would be best practice to have at least 25mm or so to spare before the frame bottoms out to the dirt).
Re-install one shock without spring to the frame mount only. Now raise the rear wheel/swing arm to the travel amount you have figured will work. Next, compress the shock to the stop and then it's a just a matter of finding where the shock needs to be mounted onto the swing arm. Make a mark on the swing arm and let the back wheel back to the ground. Confirm that the new shock position will allow full travel by lining the lower shock eye up with the mark on the swingarm. If that's all good, try clamping the shock to the mark with a G clamp or similar and then test the wheel travel. Now that you know you have found where the shock needs to be mounted, make up some mounts for the swingarm  ;D

Title: Re: Four stroke options
Post by: LWC82PE on June 16, 2016, 01:22:02 pm
If the forks are 35mm they are not PE. Assuming they are suzuki and leading axle they could either be most likely 79 TS250N, 79-81 RM100 or early 80's DR250S. Post a photo of them if you want positive ID.
Title: Re: Four stroke options
Post by: LWC82PE on June 16, 2016, 05:47:33 pm
Quote
As far as suspension goes,what part of the bike should bottom out first when your setting one up like this?The

Well I would think you want the use all of your shockabsorber stroke first and have the shock being the limit of the travel. You do not want the tyre hitting the frame/fender/airbox etc all the time and have that being your ‘limit of travel’ or 'bump stop' . Its the same thing if your front tyre hits the lower triple clamp when you still have a few inches of fork travel t go. If your tyre is hitting something and effectively being the limit of the travel, it means you need to reduce the travel. From my experience most of your extra gained travel is going to come from below the horizonatal line of the sprocket-pivot-axle due to angling the swingarm down more but the compressed length of the shocks is also going to be a determining factor aswell. To get the best end result you really need to work out shock mount positioning and shock length/stroke all together at the same time otherwise you may have a compromise. It depends on how important it is to you to get the maximum travel possible.
Title: Re: Four stroke options
Post by: James Lee on June 18, 2016, 03:32:57 pm
My calculations[guessing here]tells me when I extend the swing arm and leave all the shock mounts stock,these shocks will be the correct stroke and length,Im hoping anyway.
I fired it up today for the first time and it sounded great.Im using PWK carb,it squeezed into the manifold nicely and sounds awesome,very responsive.
Fitting a new/old stillmoto front guard and an MSC rear but have to paint them,rm125 seat and tank seem to fit great..
Ill work out how to post pics when I get the guards etc mounted properly.
Im very close to testing now.
Title: Re: Four stroke options
Post by: James Lee on June 21, 2016, 07:46:37 am
Anyone else building a 4 stroke VMX bike?I love to hear and see it.Im looking for my next build already.
Title: Re: Four stroke options
Post by: FourstrokeForever on June 21, 2016, 08:41:11 am
That was quick....How about some photos
Title: Re: Four stroke options
Post by: James Lee on June 21, 2016, 06:05:53 pm
Here it is,far from finished but together enough to test ride and make sure the box is OK.
(http://i1250.photobucket.com/albums/hh534/jameslee1977/IMG_9572_zpsolykgepk.jpg)
Title: Re: Four stroke options
Post by: LWC82PE on June 21, 2016, 07:02:07 pm
Well that looks a lot better than stock i think. From what i am seeing here, the forks are 78/79 PE175-250.
Title: Re: Four stroke options
Post by: James Lee on June 22, 2016, 07:27:58 am
Thanks LWC,the forks have some bad rust just above the seals so Ill be on the hunt for some decent ones to rebuild.
Im looking forward to tearing it down and cleaning/painting it all.
The ola inspired alloy side panels didnt turn out as I envisioned.Ill probably ditch them for some oval plastic ones.
Will report back tonight with some action pics if all goes to plan.
Title: Re: Four stroke options
Post by: shelpi on June 22, 2016, 01:23:18 pm
good work, looks the goods
Title: Re: Four stroke options
Post by: FourstrokeForever on June 22, 2016, 02:40:20 pm
Cool. Another fourstroke MX'er back from the dead.
Title: Re: Four stroke options
Post by: James Lee on June 23, 2016, 07:00:20 am
And what an awsome 4 stroke MX bike it is.On my mates tight natural terrain track this thing out corners anything Ive ridden out there.I think the PWK carb is way too big as is splutters everywhere but wide open and just when the power comes on it farts  but pulls really strong down low.I somehow lost the main jet for the original carb,can anyone tell me the jet I need?I found one that fits but it wont run right with it.
Got some great action pics Ill post when my mates comes round,there were taken on his flash SLR.
Title: Re: Four stroke options
Post by: LWC82PE on June 23, 2016, 08:31:44 am
Are you using the stock 25mm offset SP triples or the 30mm offset RM/PE triples? I cant quite fully tell by the distant photo.
Title: Re: Four stroke options
Post by: FourstrokeForever on June 23, 2016, 08:38:54 am
Good stuff James. It's great when everything you do works as planned. My hotrod XL420 is one of the best cornering bikes I've ridden as well. Funny how bikes leave the factory in an average state of handling when with a few tweaks here and there turn it into great bike...
Have fun with the carby gremlins. Sounds to me it MIGHT be the opposite of what you think in that maybe it needs MORE fuel down low. Try lifting the needle to start with. If that makes it better, also try a larger pilot jet.
Title: Re: Four stroke options
Post by: James Lee on June 23, 2016, 12:54:10 pm
Im just using the stock SP ones,would the 30mm ones be better?Does that mean my front wheel will be 5mm further forward?
Ill try lifting the needle on this carb,will give me an excuse for another test ride.Any chance of a pic of this hotrod XL you speak of?
Title: Re: Four stroke options
Post by: James Lee on June 23, 2016, 02:57:16 pm
Heres a pic of my XR600.Ive never really liked them but when my neighbor had this for sale with the gold excell rims I couldnt resist.I fitted CR500 number plates and front guard and a ne old stock stillmotor rear and the doma mufler all of which I had lying around.I rode it in practice at Bidabadaba and it went great but striped 3 gear levers and eventually 2nd let go.Can wait to get it running again.
(http://i1250.photobucket.com/albums/hh534/jameslee1977/IMG_9574_zpsipvspn2y.jpg)
Title: Re: Four stroke options
Post by: LWC82PE on June 23, 2016, 05:26:33 pm
Quote
Im just using the stock SP ones,would the 30mm ones be better?Does that mean my front wheel will be 5mm further forward?

Less off set equals more trail, slower, heavier steering, more steering effort required
More off set equals less trail, quicker, lighter steering, less effort required


Title: Re: Four stroke options
Post by: James Lee on June 23, 2016, 06:01:27 pm
Ah ok,I thought it would have been the other way round.Proves how much I know.
Heres some action shots of the SPs first outing and my mate on his MT250,We are so lucky to have such an awsome place to ride.
(http://i1378.photobucket.com/albums/ah97/Shane_Runciman/IMG_3293_zps3iorzhsr.jpg)
Title: Re: Four stroke options
Post by: James Lee on June 23, 2016, 06:04:06 pm
(http://i1378.photobucket.com/albums/ah97/Shane_Runciman/IMG_3319_zpsggt0ix1i.jpg)
Title: Re: Four stroke options
Post by: James Lee on June 23, 2016, 06:04:51 pm
(http://i1378.photobucket.com/albums/ah97/Shane_Runciman/IMG_3329_zpsoafmlzba.jpg)
Title: Re: Four stroke options
Post by: James Lee on June 23, 2016, 06:05:31 pm
(http://i1378.photobucket.com/albums/ah97/Shane_Runciman/IMG_3342_zpsskl18t4r.jpg)
Title: Re: Four stroke options
Post by: LWC82PE on June 23, 2016, 06:43:38 pm
Quote
Ah ok,I thought it would have been the other way round

Yeah you are not the only one who has thought that.
Title: Re: Four stroke options
Post by: 80-85 husky on June 23, 2016, 07:55:29 pm
must be slippery...never seen an mt 250 step out like that otherwise 8)
Title: Re: Four stroke options
Post by: James Lee on June 23, 2016, 08:29:43 pm
must be slippery...never seen an mt 250 step out like that otherwise 8)
That and the fact the back tyre is bald and probably fitted in 1980,its so slow its quite sad really.
Title: Re: Four stroke options
Post by: 80-85 husky on June 23, 2016, 08:38:07 pm
they were a sensational looking disappointment when new....nothing will change over 40 years or so
Title: Re: Four stroke options
Post by: James Lee on June 23, 2016, 08:41:15 pm
He really loves it for some reason but I just love riding with him,he really pushes that old thing round and round till he cant hold on any longer.
I pulled the main jet and it has a 160 in it.Im not sure of the size of this PWK but it has a 160 main so saying it maybe a 35mm?Im thinking a 140 main maybe more suited?The needle was on the bottom clip so someone was trying to feed it some data.
the numbers on the carb are G491 AMK2.
Im going to see the shop for a smaller jet tomorrow,any suggestions?
Title: Re: Four stroke options
Post by: TT5 Matt on June 23, 2016, 09:05:28 pm
34mm carbs off tt500's were a good swap over carb for sp370's or if you like pumper carbs a sr500 34mm carb would do and both use the twin cable setup.
Title: Re: Four stroke options
Post by: FourstrokeForever on June 24, 2016, 09:53:35 am
Great to see you running the old girl in James. Looks like you're enjoying your handywork  8)

There are pics of the XL on here somewhere, but here's some more.

(http://i1318.photobucket.com/albums/t642/markhills1/XL420/IMG_02741_zps11a7abf8.jpg)

(http://i1318.photobucket.com/albums/t642/markhills1/XL420/IMG_02831_zps5768ec65.jpg)

(http://i1318.photobucket.com/albums/t642/markhills1/XL420/IMG_02761_zps6777985c.jpg)

Since these pics I've modified the brake pedal to run over the footpeg. I've also made a new airbox along with the tail pipe and muffler as I felt the original way I had it was a bit too restrictive.
Title: Re: Four stroke options
Post by: Momus on June 24, 2016, 10:57:21 am
Nicely detailed.
Title: Re: Four stroke options
Post by: James Lee on June 25, 2016, 07:50:18 am
WOW,what a nice macine,looks like you have put some hours into that one.What shocks are those?
Title: Re: Four stroke options
Post by: James Lee on June 25, 2016, 08:03:21 am
I just picked up an IT250 81 roller,will the front end and swing arm/shock fit my XT250?
Im thinking of my next 4 stroke project already.
Title: Re: Four stroke options
Post by: FourstrokeForever on June 25, 2016, 09:03:54 am
WOW,what a nice macine,looks like you have put some hours into that one.What shocks are those?

Thanks. Yep, there were more hours put into it than I care to think about. And I wont even think about how many spondoolies it soaked up. Still, it was a labour of love and it was a bit cheaper than a C&J. The shocks are Ohlins painted in Honda colours.
Title: Re: Four stroke options
Post by: PEZBerq on June 25, 2016, 09:48:17 am
Ohlins as fitted to twin shock Huskys etc in early 80's
Title: Re: Four stroke options
Post by: cyclegod on June 25, 2016, 09:48:45 am
I just picked up an IT250 81 roller,will the front end and swing arm/shock fit my XT250?
Im thinking of my next 4 stroke project already.

Front end will fit but swingarm/shock won't, 78 YZ250/400 swingarm will but shocks are too long best to fit a custom shock from works performance etc.
Title: Re: Four stroke options
Post by: James Lee on June 27, 2016, 08:29:39 am
OK thanks.
Title: Re: Four stroke options
Post by: James Lee on July 09, 2016, 02:06:57 pm
I'm thinking of fitting my XT250 engine into the 81 IT250 chassis,any know problems?I think it would make a great bike.
Title: Re: Four stroke options
Post by: evo550 on July 17, 2016, 06:39:32 pm
I just picked up an IT250 81 roller,will the front end and swing arm/shock fit my XT250?
Im thinking of my next 4 stroke project already.
Annard and Thompson did a xt 250 with IT suspension back in 81 or 82, I have a T&T article on it somewhere, from what I remember it was an easy conversion, I'll see if I can chase it up. It would be much easier to upgrade the XT suspension than putting the motor in another frame..
Title: Re: Four stroke options
Post by: James Lee on July 29, 2016, 08:14:31 am
That would be great evo550.I'm going to see how the suspenion fits up over the next couple of days.I'm going to build a full fleat of 4 stroke MX bikes out of stuff I have lying around.My XR600 will be ready for the track soon,just had worn dogs on 2nd and 5th gears so just waiting on parts.My SP370 is hauling now with some jet and needle changes,its a great bike,just need to sort some decent shocks.
Title: Re: Four stroke options
Post by: evo550 on July 29, 2016, 08:45:55 pm
I'll chase it up over the weekend.
Title: Re: Four stroke options
Post by: James Lee on August 14, 2016, 10:51:53 am
Can anyone please help me out with some shocks for my SP?Id like to ride it more but my shocks are completly blown out.something in the 365mm range or a bit longer will work for me.
Title: Re: Four stroke options
Post by: LWC82PE on August 14, 2016, 11:06:23 am
I saw several sets of Works Performance shocks that length or perhaps 370-375mm on ebay this morning.
Title: Re: Four stroke options
Post by: Slakewell on August 14, 2016, 11:17:01 am
Can anyone please help me out with some shocks for my SP?Id like to ride it more but my shocks are completly blown out.something in the 365mm range or a bit longer will work for me.

Gazi has that length   http://www.gazisuspension.com/
Title: Re: Four stroke options
Post by: Oldfart on August 14, 2016, 12:36:53 pm
Gazi only show road bike application from what I can see....  with only 100mm of shaft travel. 
Title: Re: Four stroke options
Post by: LWC82PE on August 14, 2016, 12:59:17 pm
Yeah that's not good. On the SP or any other bike that has the shock mount back near the axle you need to have a shock with as much shaft travel as possible to get a decent wheel travel because of the lever ratio.
Title: Re: Four stroke options
Post by: Slakewell on August 14, 2016, 01:44:47 pm
(http://i1357.photobucket.com/albums/q747/Slakewell1/husky03_zps79381050.jpg)

These work fine on my husky to give 250mm of legal pre 78 travel 
Title: Re: Four stroke options
Post by: James Lee on August 14, 2016, 02:36:33 pm
I was hoping to find a set in good usable condition but I can only spend up to $400 right now.I may have to wait a while longer.
Title: Re: Four stroke options
Post by: shelpi on August 14, 2016, 03:40:01 pm
yes I would wait and save up for the Gazi's, just saying
Title: Re: Four stroke options
Post by: Oldfart on August 14, 2016, 04:01:53 pm
Do they make them with more than 100mm shaft travel ???
Title: Re: Four stroke options
Post by: mick25 on August 14, 2016, 06:22:20 pm
The Standard Tt,xt500 shocks are 365mm
Australia kedo site has brand new shocks they are yss brand 365mm long .
Title: Re: Four stroke options
Post by: Slakewell on August 14, 2016, 07:04:33 pm
(http://i1357.photobucket.com/albums/q747/Slakewell1/IMGP0534_zpsbn1znuif.jpg)

Yes they do, just ring and ask Al.

The KX is for sale.
Title: Re: Four stroke options
Post by: evo550 on August 18, 2016, 12:21:32 pm
James,
I found the article o the XT250 evo bike that Annard and Thompson built back in the early 80's.
I have posted the pics of the article on the ozvmx FB page as it's so much easier....I'm a lazy old cnut. :D
Title: Re: Four stroke options
Post by: HeavenVMX on August 21, 2016, 12:48:43 am
Now here is a real twist on the subject of this thread

An  IT465 engine into a DR250 roller  :o :o :o

http://www.ebay.com.au/itm/Yamaha-IT465-motor-in-Suzuki-DR250-frame-/172305397678?hash=item281e33b7ae:g:M9QAAOSwaB5XsACg
Title: Re: Four stroke options
Post by: evo550 on August 21, 2016, 04:36:46 pm
Is that a cut up Dr tank ?
Wonder how it would hold fuel?