500r questions & answers

[Louis Mielke]

I keep getting PMed questions on CR 500r conversion so I figured I'd start a separate thread trying to consolidate the information. I wanted to keep this separate from my official build thread. Hopefully others who have done work on 500rs can chime in with definitive information. Please no replies with heresay or guess. Only post up if you have done it yourself and can contribute to those wanting to do a build themselves.

[Louis Mielke]

500r BUILD: CR FRAME VS. ATC250r FRAME

The decision between the CR frame and the atc frame is yours to make. Weigh your pros and cons:

ATC frame

CONS: new frame cradle/ engine mounts/ alignment issues. EXHAUST issues, kick starter issues, weaker frame

PROS: bolt on front end and rear end, less custom parts

CR frame

CONS: ride height issues, front end issues, custom rear end, kick starter issues, more custom parts,
steering rake issues

PROS: bolt in engine, bolt on exhaust, stronger frame

Either build requires lots of work for it to be a viable build. There have been several built on this board, my personal opinion is that each build we've seen has had its own issues. I feel that either frame can work just as well depending on how much effort your willing to put into it.

If you want to throw one together, go for the ATC frame, its the easier build. If you want a custom project that might take lots of work to make right. Go with the CR frame. The canvas is yours to paint.

[Louis Mielke]

QUESTION: Can factory atc250r triple clamps be modified to accept the CR froks?

Yes the atc triples can be cut open to accept the CR forks. If your going to use the CR frame use 350x triples as that helps with the RAKE issue. The 250r triples have additonal rake built into them as where the 350x triples do not.

WARNING: Cutting the triples will leave them very thin. Do this at your own risk.

[SYKO]

what about cooling issues? using the stock 250r rads, I know there are pwr rads, as well how about cooling additives such as engine ice etc..etc.. also inline coolers added as well

[Louis Mielke]

what about cooling issues? using the stock 250r rads, I know there are pwr rads, as well how about cooling additives such as engine ice etc..etc.. also inline coolers added as well

I beleive KASEY or ATCTim could chime in on that but I don't beleive there aren't really cooling issues with the stock atc250r rads. I can't speak for this though because mines a bike conversion.

[KASEY]

i never have had any cooling issues till i moved to az. when its 90 degrees out i have a few issues if i don't stay moving all the time,,,, without a fan you depend on airflow for cooling,,, with some better radiators i am sure that would go away,,,, so far only one trip it was just to hot to ride,,,,

[200x Basket]

i have not had any problems with the stock 250r radiators.

[cr500=3wheeler]

I agree totally with the pros and cons, I also feel the intended use should be a deciding factor, a tight trail with trees the cr conversion would probably not have been my first choice, but then again hillracing I think the extra rake is helpful, as I have never had it on a drag strip im just making an assumption that again the extra rake would help, Of course swingarm length has to be addressed also. so as always when starting a project make wise choices, try to plan ahead and ask knowledgable people questions. Oh YA MINES STILL FOR SALE!!!!!!!!

[Bad Karma]

Bringing back an oldie... Hey Lou, I see your engine is an '86, however the cylinder appears to be from a later model, due to the water connections. Your decompression mechanism is where a water hose would be on an '86.

The general consensus over on CR500riders.com is that the later cylinders won't fit the early cases unless some machining is done. I seem to remember something about different case heights, as well. Did you get your engine this way or did you do it yourself?

I am modding my engine to use the later clutch assembly and right cover, and using a later cylinder would allow the water connections to line up properly.

[Louis Mielke]

My clinder is indeed an 86 but it was modified when the decompress was installed. The water spigot was relocated to mimic the 90s cylinders.

The only differences between the 90s and 80s cylinders is the OD of the bore liner, the decompression scallops in the liner at the exhaust ports, and the location of the water spigot. The cylinders are the same height. The height difference is in the cases. The cases are taller to compensate for the longer 87-01 rod length.

I did put my engine together by the way using the 90s clutch covers. I'd like to swap out an aftermarket basket and the newer clutch parts eventually.

[Bad Karma]

Interesting, I didn't know the water spigot could be moved like that. Good info, thanks!