ok as most of you know .... i bought an '88 CR500 motor that i will be mounting in my 250r chassis. I will be getting the crank+piston assembly balanced to help take care of vibration.... i have also considered using 1 or even 1 car motor mounts to help with vibration....

so here is my question:
my buddy seems to think that just balancing my crank+piston wont be enough to make it comfortable to ride.... i strongly think otherwise..... what is everyones opinion!!????!!!!????!!!!????!!!!! any advice or comments are accepted!!!!

 

I don't have much engine swap experience, but I believe the problem does not center around the mass of the assembly, but rather around the shake of combustion needing to be quelled by a heavy (relative) flywheel. JMO

 

I have always wondered why you don't see too many people doing this swap. A 250R chassie with the expreamly potent CR500R motor would be an unstopable combo. The problems that I can think of you may run into are listed below.

1: Motor height, The CR 500 motor gets a lot of its displacement from the stroke with makes it very tall. Mounts may be hard to fab up.
2: Exhaust system, As far as I know there is no pipe out there that will bolt on to this setup. Custom pipes are pricy.
3: Not sure exactally what the difference is betweetn say a TRX 250R motor and a CR 250 motor. I have heard lots of people say that the R motor is balanced where the CR motor is not. I am not sure if I buy this or not. I know there is a difference but it seems like an unbalanced 2 stroke motor would last about 2 minutes of running before you destroyed your main bearings so I think the issue is a little deaper then that.

 

a 500 is a little taller but it fits right in. you have to losen the rear tank mounts to change the plug. still not as bad as a sportsman 500 or srambler 500. pipes are out there you can get one from power pros who makes a lot of major companies pipes. or use a stock 500 pipe with a small dent in it where it crosses the mag side frame rail. you can even use a aftermarket 250r pipe. this has been done many time. as for vibes they dont vibe all that bad just like any other big 2 stroke if its to bad get a anti vibe steering stem dont put a fly wheel weight on they just wear out the crank bearings on the mag side. there are alot of people who have this and ride all the time so dont think its a bomb or a viberater most people who talk about the vibes have never owned one or rider one they are just repeating what they have heared so dont be afraid it isnt all that hard of a conversion .

 

im not worried about the conversion one bit. i am a fabricator at heart!!!!! and about the balancing ... its not just adding a weight... my boss said he could get it balanced by subtracting weight... down to 1/10th of a gram.. i also talked to CrankWorks out of AZ and they said that it will take care of the majority of the vibration problem.... of course i will be having the crank rebuild before this balancing is done..... does anyone have opinions on the balancing?