Found 250r chassis how hard to put CR500 in it?

[cavemanbob21]

I found an 86 250r chassis no wiring no motor just a roller and i have always had it bouncing around in my head to build a 250r with a CR 500 motor in it what all needs to be changed to do that ? simple project or fairly difficult ?

[yamaha driver]

here is a build thread on one... i know there is a lot involved http://www.3wheelerworld.com/showthread.php/135959-ATC-250R-500-conversion-build

[Mr. Clean]

"My dad is a tv repair man, he's got this ultimate set of tools, i can fix it"-Jeff Spicoli

This topic comes up on a regular basis. Most of the time responses are basically if you have to ask how, you probably should not be doing it. However, in the interest of being positive, you should provide us details about your skill set and if you have the ultimate set of tools........

[cavemanbob21]

Ya i was just looking at that before i posted this... not terribly in depth but looks like they streched the engine mounting space on the bottom and had to make some new brakets to mount it in there

[cavemanbob21]

well im an ironworker by trade i can weld and fab just about anything and my brothers been building custom quad chassis's for ice racing for years and we've never built a trike before but my tecate is close to complete and my 350x has always been perfect so its time to do somthing else ive got more tools that u can shake a stick at and im not asking for set by step here just if its a cut the frame up and the engine is still gonna not wanna fit real good kinda project or a if u have the knowledge and the tools u can do this kinda project ;) Thanks

[Dirtcrasher]

Send it to Billy Golightly and get back a frame he has got as perfect as possible after trial and error........

Or, bend/cut/hack it in yourself; Learn while your doing it.

I imagine Billy would give you some suggestions,and not a blueprint if you ask nicely.

Sometimes things are expensive, but done once and done right is my suggestion.

[4x4van]

My brother did just that, sorry I don't have pics. But there are some things you need to be aware of. Many of the "big" issues are easy to work out, but there are lots of small issues, as well. The 500 motor is narrower, and the ATC frame is wider (than the motorcycle frame) so when you shift the motor over so that the sprockets line up, the kickstarter will no longer fold out and clear the frame. You will need to custom fab the kick starter. Shifter, too, as it exits the engine in a different "frame" position than the 250 engine. Yes, he also cut and lowered the frame bottom tubes in order to stuff the 500 motor in. The 250R pipe will choke down the motor, so you will need a custom pipe with more volume in it made to fit the frame. His came out of the cylinder, to the left side, then back about 6 inches on the left, looped down and back forward, back across the front, and then followed the normal 250R pipe route on the right side. The kickstarter kicks back, not forward, so you will need to do something about the rear fender. He hinged it at the rear, so he could tilt it up backwards, start the bike, then drop it back down and latch it. Wiring harness on the 500 didn't match up (location-wise) with the ATC frame, so there were a few issues with component locations, etc.. And keep in mind that the 500 stator has no lighting coil, so no more night rides. Finally, it shakes! The vibration of the 500 (no counterbalancer like the 250R motor) WILL shake the frame apart in time. You will be constantly checking/tightening/welding.

All in all, it's a worthy project, but to do it right, it's a very encompassing project as well. You will also end up with a bike that requires much more constant attention than any production machine. It was a great dune bike; awesome power (the bottom end of a four stroke and the top end of a two stroke) with the un-matching handling of the 85-86 250R chassis (he went with a 4" extended swingarm). But after a few years, he tired of the constant work/maint and got rid of it to go back to a 250R (actually CT Racing 350R stroker motor). More fun and less wrenching.

[oscarmayer]

^ i have heard a lot of the same things.