Messages

1

Yamaha / 3R3-15618-01 Kickstart Lever Boot - Yamaha IT175, IT200, YZ100 & YZ125

« on: June 01, 2022, 07:38:48 am »

Hey guys,

I have been in collaboration with Sumo Rubber in the UK to make new kickstart boots for the 3R3-15618-01 Yamaha IT175, IT200, YZ100 & YZ125.  They fit a lot of the steel kickstarts on a lot of these models.  Took a few years, but they are finally for sale. They used one of my boots to make the replacement. Next up is the alloy kickstarts for some of the models.

https://sumorubber.com/3r3-15618-01-kickstart-lever-boot?fbclid=IwAR2Lz5nVeCJij1cC7-aHuMlU0je3rlTK9dr0SHcEX6g4PEvxY3pUu5EfAQU

Cheers,

2

Yamaha / Kick start boots

« on: February 25, 2022, 09:55:41 pm »

Hey guys,

Just got news that the kick start rubbers boots for most of the 80’s IT and YZ bikes are in pre production.
Sumo rubber sent me some pics and they look good.
I gave them samples almost two years ago, and they have just come through with the goods.

Keep an eye on the Sumo Rubber website for details. Should be in full production soon.

Cheers..

https://1drv.ms/f/s!AvgraWJNxK2SmXTyMM922spgTDnB

3

Yamaha / Re: YZ125K Rebuild

« on: June 13, 2021, 10:07:38 pm »

Hey Rocketfrog.
The K is a great bike to build and is an awesome race bike.
The gaiters are a bit big, and I can’t remember what they are. But I do have some more to try out at home, so I will post up how they fit and what brand/model they are.

As for my yellow K, I have been making minor jetting adjustments and emulator/fork oil height changes.
She is really running well, but just doesn’t quite have the pep of the white one, as the white one has the Jemco cone pipe.
I’ve got some Boysen dual stage reed valves in the mail to try out.
Will provide some settings, pics and updates on here again soon.

Cheers,

4

Yamaha / Re: YZ125K Rebuild

« on: April 30, 2021, 08:54:12 pm »

So,  Finally got the yellow K running, and its running sweet. Ive only done 3 heat cycles and ridden it around the garden, but so far it starts first kick, idles and revs great.
Me and the boy are taking them out this weekend. Im pretty confident that these two old girls are finally running in tip top shape. Once i start doing mods, they will be done very slowly and one at a time.

Check them out running here.....
https://youtu.be/NZX3o-kkod4





I guess the next posts will be where we slowly add the mods back.. and ride feedback..
Hope to also post up some pics of some meets we go to this year if we have a chance,
Cheers

5

Yamaha / Re: YZ125K Rebuild

« on: April 12, 2021, 06:09:41 pm »

OK, been a while, but still busy with bikes.
The poor old US 125K has been sitting dusty and broken for quite a while, but behind the scenes i was ordering parts and getting things built like cranks, spare cylinders etc.

The Euro K has been going gangbusters. Finally i think we have a great K. Took ages to iron out all the bugs, but i have learnt a lot and i seem to be able to build a robust engine.
We swapped pipes the other day from the OEM version to the Jemco cone pipe and DG muffler combo. The boy loved it.. Here is a short video.. she sounds sweet and really rips..

https://youtu.be/kCwyjg5IVDo

Here she is after her recent rebuild...



So this one is ready for VMX racing, and the boy loves it.. so its time for me to get the yellow K going to that i can ride as well.

First thing was to go through my shed and track everything down. I had a cylinder and new piston kit in one box over there... a crank under there.. bits and pieces everywhere.  Took ages to gather everything up and give it a good clean.

Now, heres the story.  When i blew a hole in the piston of the Euro K, i decided that the bottom end would need rebuilding. I had the good bottom end from the yellow K from when i seized that one up. So.. the new top end from the Euro K went onto the good yellow K bottom end, and thats how we got the Euro K running really well.

Now, with the yellow K.. i had the seized top end (Eric Gorr ported cylinder), and the ruined Euro K bottom end.
I needed to start from scratch. So, the bottom end was thoroughly washed out and blown out with compressed air. New main bearings were fitted, along with new main seals. A freshly built crank with new rod kit was fitted. This was all closed up with Threebond rubber gasket goo.
For the top end, the cylinder was sent away and came back with new piston kit.
I checked ring end gap. 0.5mm Perfect. I did some squish tests.. This bike also requires two base gaskets to get the required 1mm of squish. I used copper gasket spray on the two new base gaskets. I also copper coated the gasket at the reed block and used some silicon on the rubber block side.

I torqued everything up and then did the leak down test with my new Motion Pro leak down tester. Perfect.. no leaks from anywhere. All seals and gaskets holding tight at 6 PSI.



I then went through and bolted the rest of the engine together. I replace the PVL ignition with a genuine 24X stator and rotor unit. I set the timing to 1.88 BTDC using my dial gauge down the plug hole. Everything was checked and rechecked, oil added, and finally she all came together to make a nice fresh engine....



This will be going in the yellow K soon and run in.

Hopefully that will be the end of all the woes. Lots of lessons learnt over the time.
Main lessons were to check squish and adjust as necessary. Do proper leak down tests, as these old girls leak everywhere, even with new gaskets. Start stock, and slowly add mods.

I have a brand new genuine Mikuni and jets to fit up to this old girl.  Hopefully, once she is running nicely, i will slowly add the mods again. I have the bigger Mikuni to go on later, cone pipe etc.

I think one of the main reasons i kept seizing the yellow K was the PVL ignition. It was sold as a complete unit for the K, but i believe the curve was way to advanced.  I have a digital timing light and later down the track i will play with it using the stock ignition to get some base readings. I will then swap to the PVL to see what was happening there.

Anyway, thats it again for now.

Cheers,
Once

6

Yamaha / Re: YZ125K Rebuild

« on: September 02, 2020, 12:17:14 pm »

Hey Jason,
I couldn’t find the brand I used on these forks.
I’m swapping them out anyway, as they are a bit big and tend to rub.
Will let you know how the new one fit, and what brand they are.

The K is still going great. We had it at the Mx track and it’s going well.

On another note, the yellow K is just about ready to go back together.
Has rebuilt crank, new piston and ring, new VM34 with all correct jets etc.  I just have to build it all back up with new seals and gaskets.

Even my new 2T Motion Pro leak down tester has arrived, and it’s a beauty.

Will keep updating as this one come together too...

Cheers,

7

Yamaha / Re: YZ125K Rebuild

« on: August 13, 2020, 03:20:45 pm »

Time bloody flys.
Anyway, finally got the Euro K running beautifully. Persistence pays off.
My boy is big enough now to ride a 125, so I gave it to him for his 15th birthday.

After the piston meltdown, the bike was parked up. I then pulled the engine out recently, and it would need cases split, new rod, total rebuild, piston etc..

I stripped the engine down and put the crank to one side. Bore was OK, but needed acid wash and another hone.
I then got the engine from my other K. Top end blown on this one too, but bottom end all new.
So, the good bottom end was used, and with fresh gaskets, piston, ring, bearings etc..she was all fitted back together. A leak down test from my crappy home made leak down tester revealed 4 air leaks. One from the leak down tester haha, and three from the engine. Base gasket, reed block and oil side main seal. Clutch off and new seal fitted (the other one had gone hard). The other leaks were where new gaskets had been used. So I got some copper spray gasket, applied it to the new gaskets and got a perfect seal.

All air leaks fixed, ring end gap adjusted, squish band checked...everything torqued to spec, timing set at 1.88 btdc and then engine back into frame. A few more days spent cleaning, adjusting and prepping her for startup and riding.

She started OK, but wasn’t running crisp. Carb had been cleaned, but she didn’t have any mumbo. Almost sounded like a weak ignition. It still ran good enough to run her in, but the boy was disappointed.

I had my suspicions that it was the original carby.  My yellow  K has never run perfectly, and one of my ideas was to put it all back to original spec, as it was too highly modified. I had purchased a genuine 34mm Mikuni from MikuniOz and all the original spec jets including a 6F21 needle.

I set the new carb up to spec, checked float etc..and installed it.

Bang!  The K fired up and idled beautifully. Revved and run perfectly and had heaps of grunt. Sounds perfect too. Nice deep braaap...
The boy took her for a test ride and came back with a big grin and thumbs up.
Finally this K is running amazing.

The other crank has gone to the bike shop and I have started ordering parts to rebuild the yellow US K. We will be running both of them stock, and slowly adding modified parts.

Long journey this one....

8

For Sale / Re: IT175 G/H 3R6 Chain Guard and Inner Mud Guard

« on: July 02, 2020, 10:08:45 pm »

SOLD

9

For Sale / IT175 G/H 3R6 Chain Guard and Inner Mud Guard

« on: July 01, 2020, 01:52:21 pm »

Hi,

Up for sale are some great condition plastics for the IT175 G/H.
Both parts are in great condition with no cracks, tears, rips, splits or missing parts.
Quite rare chain has no chain rash or wear/splits. Will suit restored bike.
Inner mudguard still has intact rubber flap all in good condition.

Both parts for AUD $80 plus delivery.
Cheers,

10

Tech Talk / Re: YZ/IT Handlebar holder dot

« on: May 23, 2020, 04:27:07 pm »

Well done boys and thanks for the quick reply.
Amazing it is not in all the manuals, but the clamps with the dot have the same part number as just about every old school Yamaha that used 7/8 bars.
I will keep that pic for future reference.
Hopefully back on track now with some old projects.

Cheers again,
Alex

11

Tech Talk / YZ/IT Handlebar holder dot

« on: May 23, 2020, 03:13:02 pm »

Hi guys, im having a brain fart moment.

I removed the bars from all my old bikes.
Now i am struggling to remember which way all the old bar clamps go back on, and the tightening sequence.
They have the dot on top on one end.
Ive looked through all my manuals, and can't find any info on it.

They seem to fit either way, but i know their is a specific orientation and tightening sequence.
Any help for an old fart appreciated.

Cheers,
Alex

12

Yamaha / Re: YZ125G Build

« on: February 21, 2020, 11:00:39 pm »

The alloy works style tank for the G is finally finished.  Thanks to Brendon at BF Customs in WA for taking on the task.  I think he forgot how long it takes to build up a tank from scratch. Final product is amazing and will look great on the show bike..







Cheers,

13

Yamaha / Re: YZ125G Build

« on: February 08, 2020, 07:30:09 pm »

Tony, the H swingarm i am using was supposed to be an upgrade over the G.  It is 1" longer.  I got the torque arm with the swingarm so i could measure it.  After some research, i bought a 1984 CR125 torque arm.  Fits perfectly and is the same length as the H arm but looks much better in slotted alloy.
I also got Jimmy Button bend Renthal titanium colour bars.  These have a slight vintage rise and bend, but not the crazy big bars from back then.

Neale, the G came with 36mm forks, but an upgrade these days is to put the 125H 38mm forks on.  I have a set of H forks to put on the rider bike, as i think that is the best size/weight combo.  The show bike gets the 43mm Ti-Ni  forks.



Cheers,

14

Yamaha / Re: YZ125G Build

« on: February 07, 2020, 04:30:48 pm »

Thanks guys.. yep, i am guilty of "ive got one of those".. but been working hard to get some of those.  Myself and Geoff at GMC worked together to create a fantastic cone pipe for the 125G.  Fits perfect, looks fantastic and is a work of art.

Its some of the little things i like tinkering and experimenting with.  Took me a while to find some decent pegs for the G.  You can use the Stainless Steel PW50 pegs found on Ebay.  I have a set and they are super good quality and others have run them for years.  Do not buy the cheaper cast ones.. absolute junk and a death wish.  However, supporting Aussie companies is a good thing and the Pivot Pegs are a great product and fit straight on and perfect option for VMX racers with stiff and worn ankles.
I also come up with a plan to swap the 1980 steel brake arm for the 1983 alloy brake arm.  Just a bit of mild chamfering of the perch bracket and a few other small mods and it fits perfect.



Another area i have been playing around with is the shifter.  Not much out there, but for the G, the CRF50 shifter fits.  Now these come in all sorts of aftermarket brands and sizes.  BBR makes a 1" longer shifter that fits and is perfect with the bigger pegs.  Gives you a bit more room to get the big gumboots around. They also look great in the titanium colour and have a flexible tip. 



Before i tackle these projects in earnest, the workshop needed a serious refurb.  Not finished yet, but getting there.  Each station i can sand blast, weld buff, sand, paint, rebuild, etc..



On a side note.. i found a few more pics of me at 16 on the G.  It was basically Wide Open Throttle until either i broke or the bike wore out ha ha....





Cheers,

15

Yamaha / Re: YZ125G Build

« on: February 06, 2020, 09:29:30 pm »

Been a while since i posted on the ozvmx.com site.  There is a YZ125G Facebook page that i have been using lately for tips, idea's etc.

Anyway, things have been moving along nicely and i finally, just about, have two G's in pieces.  Still need a few final parts of the puzzle, but i know exactly what i need, cost and how/where to get them.

OK, the G's are being divided into two categories.  One is a rider, and the other is a show bike. Some parts that will be on the rider, will be on the show bike.  We are not building a race bike, but rather a stock, reliable G with a few upgrades.

The show bike will be nothing like original and will use a combination of some nice parts you could get back in the day, in conjunction with modern parts..

So lets get started with the show bike.....

I heard performance was not improved with a DG radial head.  But the cool factor is there from the day, so this bike had to have one.  Located a DG gold radial head for the G in Canada that the owner was willing to part with.



MotoTassinari makes a VForce reed block that fits the G.  Its usually for a Husky 125 but reported to fit and improve performance on the G. Pic below of the VForce reed block for the 1980 G, plus the DG head, and a some very rare parts in the form of a crank and 3R3 clutch.  The clutches on these old girls are all cheese, so pic after this shows the solution.



Robert Fish in the U.S makes billet clutch kits for the G.  Direct fit with instructions and all parts to make it work.



The suspension is taken care of via 43mm YZ465 forks that went to the UK for Ti-Ni treatment.  The rear shock is a new Ohlins unit sourced directly from Sweden by Russel Speak at Dynotime in Perth.. Pic below of tubes together with a nos stock size piston kit for the rider, and part of a full titanium bolt kit for the show bike..





A bunch of parts have been modified, sourced and trialed on the G.  I found that Pivot Pegz make a direct fit Yamaha peg for the G model bikes. No pin or spring mods.. just bolt straight on. They are a beaut Ozzie made peg. HotfootMoto makes intakes.. look great quality.. A mob in Queensland does hydro dipping and my airbox came back with a trick carbon fibre look.  Red64 makes titanium sprocket covers, DC makes chain guides, and EBC for the clutch plates going in the billet basket.



Local fabricator Trevor at TJO welded in some nice gussets on the upraded H swingarm..



And, finally for now, Brendon at BF Customs in Albany WA is in the middle of fabricating a works style alloy tank for the G.  Its coming along nicely... the tunnel, brackets and a few other bits have to be finished off...



There is a heap more to these builds, but i will leave it there for now.  Its all systems go, but will still take a long time.....