OzVMX Forum
Clubroom => Tech Talk => Topic started by: Ji Gantor on August 26, 2009, 01:44:58 pm
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My eyes were opened up at the nationals about USD forks and disc brakes on Pre 85 bikes.
The image below was taken at Coolum in 2006.
This YZ 490 was not ridden in a race but was prepared for Scott Bishop to ride a few laps.
I will contact Scott and ask where he got the front end from. From my memory Scott asked Yamaha to supply the parts which became a gift to the bike owner afterwards.
Are these modifications legal like Glenn Bells bike?
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/PB100200.jpg)
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Would that be Billy Nolan talking up the big Yamaha there?
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Hi Firko,
The only people I know in that image is the fellow closest to the camera on the right hand side, that is Scott Bishop.
The fellow in the back ground with the red cap and yellow sleeves lent me a nut that secured my YZ490 kick lever to the gear box. Thanks mate if you are on the forum.
Ji
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USD forks and a two piston disc brake calliper.
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/USD1.jpg)
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The degenerate in the red cap and yellow sleeves lurking in the background would be OZVMXs resident hippy Holeshot Buddy, aka Russ Williamson, and yes Firko, that would be young William Nolan yakking away in the foreground.
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That is right the two Steves in the bus told me his name was Russ.
Ji
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We should widen this topic to include all classes.
Take for instance these CNCed triple clamps for a Pre 78 Maico.
How on Earth are these legal?
The original Maico clamps only have one row of bolts top and bottom.
They also do not clamp from the side.
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Billettripleclamp4.jpg)
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This is what the original Maico clamps look like.
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Day1d.jpg)
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if it works why change it
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The Americans are a lot more tolerant of CNC'd bling on VMX race bikes than we are. Don't know what their rules say, but ours don't actually prohibit it (or, at least don't effectively prohibit it).
We seem to depend a lot more on peer pressure to stop this sort of eyesore on our race bikes - and there seems to be a lot more tolerance of it on the later era VMX bikes (for better or for worse).
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ji if your going to put those monstrositities tripple clamps on can i have the old ones for a real maico ;)i/ll
find some thing for them to go on one day
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Hi Paul,
This is the same forks, frame and triple clamps.
After the Ji Gantor treatment of course.
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Maico1.jpg)
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Ji the bike Scotty rode at Coolum that day is another one of Geoff Holmes bikes.
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thank god for that lol can you post a pic off the finished bike please
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i think a mod that should be legal in pre 85 is fitment of a disc front as long as it is within the realms of the period , my view comes from a safety point , running a bike with drum against disc bikes (esp. the faster classes)can be hazadous , unless u want to just follow them around , i guess at club level it doesn,t matter too much , the caliper on the 490 L above seems to be yamaha ,s 84 xt 600 , comments anybody ?
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Can't see why it would be any more hazardous than it was in 1983 or 84.
The disc braked Yamahas grate on me a bit, to be honest - I've seen plenty with Z-spokes and 43mm forks running as pre-85, despite the fact that they're clearly 1985/86 model parts....
If someone wants to adapt disc parts from a 1984 XT (or a 1984 anything), then that's 100% within the rules and the spirit of the category.
Seeing as a pre-85 Honda front end goes into a pre-85 Yamaha so easily, you'd have to be exceptionally one-eyed to bother with the XT stuff.
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just useing the xt as an example , yep same issues as 1984 , and i bet all sorts of conversions were done then as well ?
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that bike was prepped by owner geoff homes as johnny o said
for scott to ride if i remember well he didnt like it
and then wrote a report in a mag about riding old dinosaurs
and how bad it was ;)
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Nathan the Z spokes and 43mm forks were on YZ's in '84 with a drum brake. Like you said it would be perfectly legal to fit a '84 CR or KX disc brake front to a YZ for pre '85.
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Nathan the Z spokes and 43mm forks were on YZ's in '84 with a drum brake. Like you said it would be perfectly legal to fit a '84 CR or KX disc brake front to a YZ for pre '85.
Yes you're right. I was a bit vague.
If its got Z-spokes and a disc brake, then it isn't pre-85 legal.
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my view comes from a safety point , running a bike with drum against disc bikes (esp. the faster classes)can be hazadous , unless u want to just follow them around
Pick a different line or get a good start. Cheaper than playing around with front ends..... ;)
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Hi Johnny O and Holeshot Buddy,
So Geoff strikes again.
Two Pre 85 bikes with USD and disc brakes.
The story on the day goes like this.
My brother was talking to Scott about the big YZ an told him that he had one back in the day, Di Gantor also told him that they handled like pus and that everybody back then knew that. Scott being a Yami men was unbelieving but after his ride he decided to call some Yami guys in the States. The next time Di rode on Scott's track (out the back of the petrol station) Scott told Di that he was right, the guys in the States confirmed what Di had said. So I guess Scott decided to write about his new found knowledge.
Ji
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Okay, you guys are great.
So the Honda CR500 1984 front disc brake assembly fits the Yami.
This is good, I will start looking for the disc.
Ji
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Here you go Paul,
My Maico's first outing was at the Conondale Classic last year.
Enjoy
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/Maico77.jpg)
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i had a brief conversation at a practice day at a local track where Scott Bishop was talking about the YZ490 that was being prepared for him to ride at coolum. he didn't seem as excited as i would of thought about it all but i do recall him saying his only request was that the bike have upside down forks and a disc brake or he wouldn't ride it.
i doubt it's pre~85 legal, as thats not what it was built for.
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Hi Vandy,
With that line of thought Glenn's bike would not be legal then.
Ji
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yeh but glens forks are pre 85 and the brake kit is to
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i doubt it's pre~85 legal, as thats not what it was built for.
im of the impression that the bike wasn't built for pre~85 competition.
rather, the bike was built with a modern front end so the rider looked cool doing a few demo laps.
theres a difference.
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I see.
Thanks Vandy.
Ji
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i know the yamaha geoff built and it had period correct front end and brakes
same as glen bells bike he did it up for himself
not for scott bishop
he just sponged a ride at legends day at nationals. most bikes were supplied to riders
i know i supplied four. darren smart,brian flemming, didnt complain
about the bikes they just enjoyed the moment and caught up
with everyone we all had a great day
there was more people around our display
than there was at the factory teams ;)
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Thanks Holeshot Buddy for clearing that up. Do you know what forks and brakes they are?
Thanks you for giving me that nut to hold on my kick lever at the Nationals, it worked a treat.
I have just installed the OEM nut and have another in my tool box if required.
Ji
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So, are the USD forks Pre 85 legal or not? Were they really around in 1984?
Tex
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So the story goes Simon's released a set in 1982 and WP also had a pair for sale.
So if these are the Pre 85 models which so many have suggested that they are then yes these two bikes are period correct.
The Simon's USD of that period cost $5000.00 if you can find a pair.
Ji
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simons forks were availiable to the public in aust
in 1983
white power were in 1984 on production ktms with drum brake only
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So Holeshot what type of USD forks are they on the bike Scott rode at Coolum?
Ji
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For a bike to run in that configuration (and be considered legal) you would need solid evidence that a bike raced using those components prior to the cut off date. Just because a component was available doesn't automaticaly make it kosher.
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So the story goes Simon's released a set in 1982 and WP also had a pair for sale.
you have done your homework JI! yes there were early WP4054's back around 82, most likey only in europe and as prototype/test models/limited sets made before the production set came out on 84 KTM's No one can yet confirm exactly when they were available as aftermarket forks yet though.I have listing for WP4054 Non adjustable -revsion set #R601 1982-1988.
In my opinion, if you get a set of drum brake 4054's off a 84 KTM and then machine your own lower axle mount/cailiper carrier for your YZ with CR forks or what ever you want them for? then that would be perfectly legal because A) The forks are off a pre 85 model and B) the caliper carrier is custom made and not a off the shelf part from a later model as back in 84 someone could have done exactly the same thing and wanted 4054's on a yamaha or honda or what ever and got a set off a KTM and then decided they wanted a disc but from what i can gather there was no WP 4054 caliper carriers at all in pre 85 so they would have had to make their own. There is debate whether a 1985 or 1986 set of WP4054s are legal for pre 85 even if they are proven to be the same design internally and exteranlly as the 84 KTM forks even if you convert to drum brake or take off the 'factory built' 85 or 86 caliper carrier and built your own, so the only way i think you could safely do it with no arguments is to use a 84 KTM set of 4054's or one of those earlier limited production/prototype sets from europe the later which you would never find anyway.
There was a set of 'works' USD Ohlins forks on ebay this year, i dont think i saved the photos but there was some history behind them origiinating back to Belgium? The seller said they were 82 models however forum member Marc FX believed they were 85 model Ohlins USD forks and not 82 as the ebay listing said but he or the seller may not have been right or wrong.
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Ji
You may have already seen it, here's a thread on another forum about Simon's forks.
I can't seem to link it with it translated.
http://www.mxteam.com/forums/lofiversion/index.php/t19123.html (http://www.mxteam.com/forums/lofiversion/index.php/t19123.html)
Noel
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Hi NSR3,
I see the Simon's forks but do not speak French so the words are all Dutch to me.
The axle connection at the base of the forks are very similar to Scott's bike, they must have been milled up.
Thanks mate
Ji
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the forks on the yz 490 were simons
geoff still has the bike ;)
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Ji
Google it, then click on translate.
Noel
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JI its french, just go to babelfish to translate it. It worked for me.