OzVMX Forum
Clubroom => General Discussion => Topic started by: Slakewell on December 29, 2012, 01:47:00 pm
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Not trying to start a shit fight just a simple yes or no.
XR 200 engines, The 1980/81 XR 200 was twin shock , the motor did not change until 84 thou the frame changed too single shock in 82, then the engine returned in 86 till late 90's
Are the later engines follow on and legal for evo twin shock?
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I hope so. I'd love to see one go up against a YZ 250 H....... :)
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please answer I would love to hear the outcome, so with the same engineering ruleing how far can you go ? and takeing TS400 ruleing into account ???
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I'm Gunna say no, reason being the follow on rule was based on complete bikes, not components. If the motor came from a single shock XR then technically it's not legal in the evo class.
Didn't the twin shock XR's have points ignition run off the cam, and single shock went to electronic?
.......but who is ever Gunna know?
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Twin shock was CDI most parts are Identical or not visually distinguishable,
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There was 1979 manufactured Honda XL 185S, I got a frame from a wreckers for $50 they had a whole bike for $450 that would get you into the pre 80's Twin shocks,
Stroker crank 70mm big bore 249cc of fun
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So what has electronics got to do with it?
If we had to rely on old spark systems on the side cars we wouldnt have any
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Would it be the same as a cr480 motor in a twin shock frame? It comes out of a single shock bike so it isn't allowed.
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Would it be the same as a cr480 motor in a twin shock frame? It comes out of a single shock bike so it isn't allowed.
Normally that would be right but if the motor appeared both in a twin shock frame and a single shock frame then I think it would be Evo legal.
Assuming that the motors are identical, which means cases, head barrel and gearset.
Ignition methods are optional.
Other motors that I believe fall into the same category are the first four stroke Husky 510 motors
and the
82 Maico 490 motor which appeared in the MX single shock and the GS twinshock
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So what has electronics got to do with it?
A fair bit if your trying to prove that two different era motors are identical, if one had points on the end of the cam and another didn't then they aren't identical, similar, but not the same.
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My understanding of the follow on rule was that if it was identical externally then it was acceptable.
I'm sure there is plenty of up-to-'84 XS650 donks getting around in Pre '75 chairs, with different cranks, cams pistons, clutches, gearboxes and ignitions...
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These threads drive me nuts.
Imagine you had an 82/83 motor in bits on the bench, and an 86+ motor in bits on the bench, and all the parts were jumbled up.
1. Any part that is identical or cannot be reasonably identified as 86+ is legal for pre-85.
2. Any part that cannot be seen from the outside is effectively legal, even if its different* (subject to the usual restrictions to the number of forward gears, and the bike being entered in the correct capacity class).
If, for example, the 86 has a higher compression piston or bigger cam, then that's 100% legal as the internal parts are essentially free.
If, for example, the pre-85 motors were only 5-speed (they weren't), then the later model 6-speed would not be legal.
If, for example, the 86+ motor has a different head casting with more fins or something, then that's not legal (but highly likely to be ignored).
If, for example, the 86+ motor has a different head with a centre port rather than a side port, then that would not be legal.
If, for example, the 86+ motor had a longer conrod and a taller barrel, then the longer rod would be legal, but the taller barrel would not.
*This is not 100% technically correct, but it's how it works.
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Ignitions are specifically allowed to be swapped from points to CDI, with the only real condition being that the motor must appear era-correct from the outside.
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What about performance parts from the same era.
Eg fitting a DG cylinder head ? Or DG swing arm?
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1979 XR185 visually the same and Pre 80 Legal
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So if you put a points cover on it as from memory the cdi cover has 'Cdi' on it, then it would look exactly the same.
I really don't see why you would want to reverse engineer like that. You will be a sweep rider running that!
Each to their own eh ???
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Brads on the money, its an XR200 why bother with such a land crab.
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Nathan, your using pre 90 class components being used in the pre 85 class as an example, the question was on the evo class eligibility.
2012 M.O.M's page 167.
Acceptable Machines and components Evolution class.
18.5.6.1 Bikes will be OEM (original equipement manufacture).
18.5.6.2 Modifications converting later equipement to comply will not be allowed.
18.5.6.2 All components will be of the period the machine was manufactured:
a) No linkage suspension.
b) No disc brakes.
c) air cooled motors.
Slakewell,
Those are the rules, interpret them how you will.
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the xl185 had cdi ignitions
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I used ignition from a postie bike on my XL pre 75 racer back in the 90's , I guess that dosent mean it was legal just no one cared.
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Methinks you blokes are putting way too much thought into this ::). This is how eligibility paranoia gets its hold on us, turning insignificant little sideshows into major dramas (see RM-B/C alloy swingarm debate elsewhere on the forum). I can't see a scrutineer giving a holy damn about how many shocks the donor XR200 motor had, just use it for Evo and I'm pretty positive nobody will give a shit.
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Nathan, your using pre 90 class components being used in the pre 85 class as an example, the question was on the evo class eligibility.
You're right. I may have had a couple of beers last night, and the attention to detail may have not been all that good...
:P
Still, the points I made are valid - just add a 1979/80 motor in pieces to your pile on the bench. ;)
There may be some differences, but my understanding is that all 2-valve XR200 motors from 1979 to the very last of them are identical or very close to it.
I see this thread coming back to the idea of 2012- built "replica parts" being acceptable, but everyone thinking that 1990 built replica parts being dirty cheats... ::)
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Methinks you blokes are putting way too much thought into this ::). This is how eligibility paranoia gets its hold on us, turning insignificant little sideshows into major dramas (see RM-B/C alloy swingarm debate elsewhere on the forum). I can't see a scrutineer giving a holy damn about how many shocks the donor XR200 motor had, just use it for Evo and I'm pretty positive nobody will give a shit.
Oh I don't know Firko, The question was on eligibility, so an appropriate answer had to be given. No, in my opinion.
If the question was "Would anyone give a shoot if....." then your angle would be on the money.
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You're right Evo but so many of these hypotheticals come up on the forum you'd think out sport was a secret society full of deceitful cheats perpetually trying to pull big swiftys over the scrutineers and their fellow racers. The truth is that our rule book maps it out pretty well for those who just want to build a bike to race. If it's not in the book, common sense should tell you if it's legit or not, and 99.9% of us use that common sense and build bikes within the set parameters. If the XR200 engines are all the same I doubt anyone but the engine number Nazis would know or care. Has anyone ever cared that a '76 XL350 motor (fitted with a side port pre 75 head of course) was used in pre 75? No. Has anyone ever bothered to protest anyone using a 1976 Suzuki TS400 bottom end in their TM400? I doubt it, I can recall a champion Suzuki rider telling the scrutineer his bike had just such a motor and the scrutineer didn't even bat an eyelid. The 1972 RT2 bottom end in my pre 70 Cheney-Yamaha is quite legal purely by being a flow-on...and so on, there's plenty more examples out there. It'd be the same if you showed up with our hypothetical XR200 engine housed in a twin shock XL. I'm absolutely sure it'd be just fine ;)
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Maybe you're right Evo but so many of these hypotheticals come up on the forum you'd think out sport was a secret society full of deceitful cheats perpetually trying to pull big swiftys over the scrutineers and their fellow racers. The truth is that our rule book maps it out pretty well for those who just want to build a bike to race. If it's not in the book, common sense should tell you if it's legit or not, and 99.9% of us use that common sense and build bikes within the set parameters. If the XR200 engines are all the same I doubt anyone but the engine number Nazis would know or care. Has anyone ever cared that a '76 XL350 motor (fitted with a side port pre 75 head of course) was used in pre 75? No. Has anyone ever bothered to protest anyone using a 1976 Suzuki TS400 bottom end in their TM400? I doubt it, I can recall a champion Suzuki rider telling the scrutineer his bike had just such a motor and the scrutineer didn't even bat an eyelid. The 1972 RT2 bottom end in my pre 70 Cheney-Yamaha is quite legal purely by being a flow-on...and so on, there's plenty more examples out there. It'd be the same if you showed up with our hypothetical XR200 engine housed in a twin shock XL. I'm absolutely sure it'd be just fine ;)
Yep, 99.9% correct, now if you where to remove the "Maybe" that started your post, I would be 100% happy. ;) ;D
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Not to cause any problems and I'm sure it has been talked about before, but why is any RT (360)Yamaha pre 70 legal? I thought only the DT was made before 1970. Does a pre 70 Yam have to have a square swing arm?
I think the rules should become freer not more restrictive. Especially with trail bike based racers.
Cheers, Grahame
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Very early in the piece the RT1 was included as a flow on to the DT1. I know that sounds a bit bogus but it's never been a problem and it's pretty fair on the RT1 as it really wouldn't cut it as a pre 75 racer. Initially the DT1 had to have a 'square' swingarm but when the RT1 became legalised that rule became irrelevent as the RT1 has a round swingarm.
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......."Has anyone ever bothered to protest anyone using a 1976 Suzuki TS400 bottom end in their TM400?
answer is NO - because it's an acceptable flow on model as described.
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Insert Quote
......."Has anyone ever bothered to protest anyone using a 1976 Suzuki TS400
bottom end in their TM400?
answer is NO - because it's an acceptable flow on model as described
That's my point Oldfart, although when the situation I described occured it wasn't considered a flow on.
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Point taken ;D wording was only changed in 2012 moms issue. ::)