good vibes...

[wilkin250r]

I have a 250r (spare engine), my girlfriend has a 400EX, so you can give me answers for both.

Big bore kits like a 440EX, or a 350r produce alot of vibration. How do I maximize power without producing too much vibration? Maybe instead of a big-bore 440, I go with a 416 and a stroker crank? (or a 265 and stroker for the R?)

Do the stroker motors produce as much vibration as the big-bore kits? It will obviously affect reliability, is it really bad, not worth it?

bigbore:more vibration...bigger piston...ok reliability...high reliablilty with oil cooler...lots more top end of the gears

stroker:less vibration...longer rod...great reliabilty...lots more money....lots more torque

either way i would say is worth it...but a 440 also requires a new piston...gaskets...cam...porting...and more to be efficient...so u may want to go 416

[wilkin250r]

Maybe I just go stock bore and a stroker, which should take it to about 435 or so.

I don't really care that it is going to cost more. Doesn't a 440 require case machining to accept the bigger sleeve? Between splitting the cases to machine them and buying a new sleeve, or splitting the cases to replace the crank, there isn't going to be a huge price difference anyway...