cr500 motor in 400ex frame

[bansheemorphine]

i have heard alot of different opinoins on his motor in a quad frame some saying it is not ridable due to the vibration but i have heard of it done has anyone on this forum done it or heard about it?

[bwamos]

Well.. I haven't heard of 400ex frames being used.

The CR500 motor fits much better into an '86 style 250r frame. Motor's not counterbalanced.. so the frame will need to be modified to absorb that vibration.

However.. I have seen 400ex frames being used with the old XR650 air cooled motor. And the 450R frames being used for the water cooled XR650R motor for desert racers.

[bansheemorphine]

modified for the vibration how so?

[bwamos]

Couple different ways.

Most common, is to add more gusseting, and double wall some of the tube frame points. so the welds wont crack from vibration.

Another method is to add, anti vibration motor mounts like what's used in some harleys.

Or both.

Best bet is to use a LT500 motor. It's already counterbalanced. ;)

[Toadz400]

Originally posted by bwamos
Couple different ways.

Most common, is to add more gusseting, and double wall some of the tube frame points. so the welds wont crack from vibration.

Another method is to add, anti vibration motor mounts like what's used in some harleys.

Or both.

Best bet is to use a LT500 motor. It's already counterbalanced. ;)

CR500 engine is going to be a little bit more powerful though, coming from a dirtbike. I would try the anti-vibration motor mounts and adding rubber bushings anywhere else.