OzVMX Forum
Clubroom => Tech Talk => Topic started by: shanefz6 on August 11, 2009, 11:25:30 am
-
Hi all im going to go racing next year on a stock std RT1. Just wondering if there is anything i should be doing to it to make it better. Im looking at getting some rear shocks at the moment but have no idea any suggestions would be a great help.
-
Start at the front.
-
Hi all im going to go racing next year on a stock std RT1. Just wondering if there is anything i should be doing to it to make it better. Im looking at getting some rear shocks at the moment but have no idea any suggestions would be a great help.
How much money have you got ::), or willing to spend :-\.
1/ I suggest for safety and enjoyment start on the suspension and make it as good as the rules allow - new rear suspension and new PDS valving or sim for the front.
Lighter hubs front and rear will help the suspension. Careful selection should get a better combination of weight, braking power and strength compared to the Yammy originals. (I'm assuming a 21inch wheel already).
1a/ For the same reasons I suggest you improve the handling by lowering the engine within the frame.
2/ HP. Improved exhaust (chamber), improved intake (carby size and airbox), improved porting.
To achieve the above you can go straight to old bits like GYT kits, and individual GYT bits, after market, like the head been offered on Mark's Swap Meet, or mod your own parts using modern knowledge to get the most out of the bits.
http://ozvmx.com/community/index.php?topic=9007.0
http://ozvmx.com/community/index.php?topic=8959.0
Now cue Vandy and Lozza ;D.
-
3/ CR gearbox from MX or YZ. Not 100% on this (yet) but have been told its possible.
Now cue Vandy, Lozza and Mark AC.T. (for g/box);D.
-
If you want to fund Geoff's retirement you could get him to run you off a copy of one of these, he does it all the time......
(http://i323.photobucket.com/albums/nn458/mx250syd/big26rs.jpg)(http://i323.photobucket.com/albums/nn458/mx250syd/big26ls.jpg)
-
Here's some inspiration for NOS if your budget or taste don't run to the exotic of a Rickman........
(http://i323.photobucket.com/albums/nn458/mx250syd/montesa/e07c_3.jpg)
-
Here's an article on frame lowering. I think Vandy has done this so he might chirp in with advice shortly.
(http://i323.photobucket.com/albums/nn458/mx250syd/RT1/ozvmx_0001.jpg)(http://i323.photobucket.com/albums/nn458/mx250syd/RT1/ozvmx_0002.jpg)
(http://i323.photobucket.com/albums/nn458/mx250syd/RT1/ozvmx_0003.jpg)(http://i323.photobucket.com/albums/nn458/mx250syd/RT1/ozvmx_0004.jpg)
-
(http://i323.photobucket.com/albums/nn458/mx250syd/RT1/ozvmx_0006.jpg)(http://i323.photobucket.com/albums/nn458/mx250syd/RT1/ozvmx_0007.jpg)
(http://i323.photobucket.com/albums/nn458/mx250syd/RT1/ozvmx_0008.jpg)(http://i323.photobucket.com/albums/nn458/mx250syd/RT1/ozvmx_0009.jpg)
-
Last one ;D
(http://i323.photobucket.com/albums/nn458/mx250syd/RT1/ozvmx_0010.jpg)(http://i323.photobucket.com/albums/nn458/mx250syd/RT1/ozvmx_0011.jpg)
(http://i323.photobucket.com/albums/nn458/mx250syd/RT1/ozvmx_0012.jpg)
-
Hey Shane,
{is my cue timely?}
i've just fininshed racing my RT1 at the 09 Conondale Nats. she's pretty stock~ish and a heavy bike by comparison to the competition but it ran around 8th place in the first 2 races and dnf~ed the 3rd with a broken throttle cable on the first uphill.
Chassis*
get some good shocks=yes
do the best you can with the forks as well.
thats pretty obvious info right.
do the engine lowering in the frame mod. mine has been lowered 2" and is a much better bike.
there heaps of info in this forum already in reguards to the frame mod.
it'll turn up if you go looking.
i use triple clamps from a later model DT with high rise bars and overall it's about as good as it'll be.
the 125 front hub is smaller and lighter. ;)
remove the steel rear guard and make up a plastic inner guard to trim more weight.
weight*
just get rid of as much of it as you can.
engine*
pipe is a good one to have although i used my stocker for a while till i sorted my pipe.you can run into overheating issues with the stocker but it's rare.
34mm mikuni jetted to RT1MX spec
if you value you right leg,teeth and general well being, replace the points ignition with a cdi unit or the "kick~back" on start up will kill you..
the later big bike DT units will bolt straight in and a flywheel weight of 1650grams is spot on for tourque..
my porting and head are STD but are the next things i will be looking to do.
lube the crap out of your clutch cable and clutch worm/gear. fit lighter clutch springs if you can.
my aim has been to slim the bike down a little too as some of the "leg burner" pipes tend to make the RT1,s feel pretty fat. mine tucks in under the frame rails in the leg area and my seat is from an MX125a yammie.
i love my Rt1 but it's not for every track. if your on a pre~75 friendly track then cool but if the going gets tough then you'll need to ride it smart.
thats a heap of info and will take a little time but they're a fun bike. if you need any more info, feel free to give me a hoy and i'll see if i can help.
cheers,
Vandy.
-
heres a link to a previuos topic and theres a photo of my blue RT1 in there with frame lowered etc
http://ozvmx.com/community/index.php?topic=7306.0
in that topic is also another link to even more RT1 info.
are we mad or what?
gee Greame, you reckon you got enough info in this thread already? ;D
-
gee Greame, you reckon you got enough info in this thread already? ;D
Nope! He's just a novice. I've got to 'kill him with kindness' and 'sucker' him in, get him hooked, spread the disease 8). If I'm to be afflicted so's everyone else ;D.
Congrats on ya ride :). 8th ain't too shabby at the Nats on an old clunker like the RT 8) - the good fun is a bonus after that :D.
-
Thanks to all the people that replied.
I think the frame mods will keep me going for a short while.
If you think of anything else i should use or do just let me know.
-
I've been racing a fairly standard DT1, and have ridden Vandy's frame-modded RT1.
The frame mod is definitely helpful, but not essential for a novice racer.
My general view is that the most important thing is to have a bike that you trust and are comfortable on, with everything working as well as it should, and you'll be fine. You'll hear a lot of talk about trick shocks, PD valves, etc etc and these things do help - but they're definitely not essential for a novice racer to have a good time and be reasonably competitive.
Remember: Last place in the race beats first spectator everytime!
-
Hey Shane,
I agree with Nathan, I have only done two meetings on dirt track (about 12 short races), Nathan told me get your bike to 95% and just do it. I bet that you won't come last anyway.. I asume that you have not raced before. Its a buz, hell of a lot of nice people too
OLDYZMAN
-
No doubt the Rickman Replica probably does most things better but I reckon there is nothing wrong with visual appeal of the black RT1 above. Had forgotten had good they looked.
-
There you go Col, for a man with a fine sense and good taste in Motorcycles ;) :D.
(http://i323.photobucket.com/albums/nn458/mx250syd/rt1enduro.jpg)
-
Here's a few more Col, and Shane.........
(http://i323.photobucket.com/albums/nn458/mx250syd/RT1/0c39_3.jpg)(http://i323.photobucket.com/albums/nn458/mx250syd/RT1/2ee6_3.jpg)
-
Nice. Thanks for posting MX250. Are the static shots of a local bike.
-
Nice. Thanks for posting MX250. Are the static shots of a local bike.
kind of looks nth amreican/canadian fauna in the background but i love the polished finish on the engine cases. i reckon the early yammies, RT/DT/CT/AT etc lend themselves to the polished case look.
cool bikes Greame.
me thinks you've got it bad.... :D
hows that Hallman DT/YZ project coming along? any advancments?
-
My first serious race bike (I can't count the Sherpa S as serious) was a yellow stripe genuine RT1MX I bought off touring car racer Pere Geohegan. Apparently he'd imported it into Australia in the boot of a Ford Mustang when both were brand new. I only raced it a couple of times before I bought my precious old 350 Maico but kept it for a while until I sold it to a mate. I agree with Vandy and Graeme the black tank RT1 is the goods in the looks department. The memory of that bike prompted me to build the 'Dt1 from Hell' (christened that by Geoff Eldridge) in 1990 for vintage racing. GE had picked up a clean original '68 model so we decided to do a dual build for ADB, mine a racer and his a street legal full resto. While GE kept getting side tracked with other projects, I finished mine and raced the bike with mixed results, the best a second to Boagy in pre 70/250 at the 95 Nats and 2nd at the Cherabah Nats again to Boagy and his CZ sidepiper with Kevin Flood on board. This is the bike that ended my racing career when while practicing at Pacific Park the throttle stuck on sending me over a berm flat tap in 4th. I ended with 4 broken ribs, a broken collarbone, badly broken elbow and three broken fingers. Ironically, my crash happened the same day GE was killed in Nevada. Eventually I came into possession of the unrestored GE DT1 and I restored it in his honour. Because the DT1 had a Warren Willing ported barrel that was like a light switch I had planned to fit an RT1 engine but the crash ended that dream. Now, 16 years later the engine is sitting in my under construction Cheney Yamaha which will hit the dirt sometime soon.
Below are some photos of the DT1 when it was first built. By the end of it's racing days it'd gained a Webco head, a politically incorrect Peter Reynolds fat pipe, 2"extended square section swingarm and gone on a diet of methanol. The frame modification are many including grafting front downtubes and steering head from an OSSA SDR, lowered the engine cradle 2", reduced the rake from 31 degrees to around 28 degrees, OSSA triple clamps and forks, Phantom dampers, OSSA front wheel (hopeless brakes), Yamaha MX250 back wheel, Boge shocks later replaced with Works Performance, NOS tank '69 model tank found in Melbourne, genuine rare as shite GYT alloy front guard, fibreglass replica rear.
The engine has a YZ250 A gearbox, YZ250A clutch, radically ported barrel by Warren Willing, Webco head, DT2MX,Peter Reynolds modded GYT head and ACK heads at different times, DT400 CDI with MX250 black box, GYT pipe at first then a Bassani then Peter Reynolds fatty pipe. I've got 2 RT1 engines #1 has mildly modded ports, RT2MX head, DT2MX gearbox, YZA clutch DT400 CDI ignition . Engine # 2 has a stock NOS GYT barrel, ACK head, DT2MX gearbox and clutch, PVL or DT400 ignition. I'm using a Pro-Form YZ360A pipe which fits the unique Cheney frame and airbox almost perfectly.
(http://img.villagephotos.com/p/2005-8/1062154/dtfhfirk.jpg) (http://img.villagephotos.com/p/2005-8/1062154/dt1fhfirk3.jpg)(http://img.villagephotos.com/p/2005-8/1062154/dt1fhfirk2.jpg)(http://img.villagephotos.com/p/2005-8/1062154/DT1ADBFIRK.jpg)
-
If you want to see a cool DT1 look on the for sale section not just because its my bike but I just love the look of it 8) jimson