CR500 Engine in the 400EX?

[433rd]

I've been thinking about going with this combo. Anyone here done it?? If so, I'd like to hear about it.

It sure would be one mean and pissed off EX!! Should be a little lighter too. The Exhaust is one thing that I think might be a little tricky.

Any comments, pro or con?

[Extremeracer167]

well vibration would prob. destroy the mild steel frame in a heartbeat! I think the conversion would actually be fairly easy, but keeping up on the frame would be a chore of its own!!

[433rd]

I think it would need a better frame as well, it would be subjected to quite a bit more stress than the stocker frame was designed for. An aftermarket Chromoly frame should take care of that.

[krazykurtk]

I know a guy building one. The guess the CR motor fit in very well. Yes he is having the pipe custom made for the machine. I haven't talked to him in a couple of weeks to see how the project is progressing. I also know of another person that rode a bike like this a few years back on the ice. Said it vibrated so bad his hands went numb. I can't wait to see it in it's complete form and give it a whirl.

[L.Vegas400]

if the vibrations are so bad, how can you ride the bike the eng came in and not go numb?

[OutlawEX]

Originally posted by Extremeracer167
well vibration would prob. destroy the mild steel frame in a heartbeat! I think the conversion would actually be fairly easy, but keeping up on the frame would be a chore of its own!!

Yes man i agree with him the vibration is gonna play a big factor,But my friend put a 350X motor in his 250R chassis and it was fine but then again its square tubing unlike the 400ex whitch is round

[Extremeracer167]

Lets keep in mind, im sure all of u remember the sweet ride Yokley was on with the KXF-250. He was running a Roll Chassis and that thing even cracked afew times due to Vibrations. He even cracked some nerf bars he said from the thing vibrating so much. If u can keep up with the frame, ide say GO FOR IT!! But if not, its going to be a nightmare for you! **** my frame even craked with a 400EX engine in it, and it has a counterbalnce!

WHy the vibration isnt so bad in a bike.....i have no idea. There is still alot of Vibration in a bike, just for some reason it isnt as noticeable.

just slip some hunks of rubber between the mounts and the engine! that will take car of your vibe problems! good luck man

[433rd]

I was thinking about that after the above comments. I'm sure some sort of bushing type mount could be designed into it. Although, I learned in my earlier stock car racing days, when you go away from a solid powertrain mount, you will loose some torque. I guess with a 500cc 2 stroke in a EX type chassis, loosing a little torque wouldn't hurt too much!! :D

[JabberJaw]

I'm going with the XR600...

[Sick0]

I seen a quad in the magazine that had a 2002 cr250 motors in it and he use solid mounts for it. And it didn't vibrate that much I guess. The frame was made for the motor thoght.

[Extremeracer167]

Yeah they didnt just throw it in a stock mild steel frame. It was a chromoly frame. U are tlaking about the Fischer one right??

[Sick0]

Yup thats the one. Yeah I know he built that frame just for that engine.

[Extremeracer167]

I cant remember if they say that was bad in the vibration department, but remember that is a WELL BALANCED 250 engine. Thats one thing honda aimed for. The CR500 isnt quite up to that par, lol

[Sick0]

I think they said Its wasn't that bad. Better than they expected from a dirtbike motor with solid motor mounts.