Small Engines (Lawn Mowers, etc.): 1991 suzuki lt250r quadracer, suzuki lt250r, balance system

Question
Hi, i recently split the cases and rebuilt the topend on my quad. do to a broken wrist clip i had to bore my cylinder .040 over.  The operation went smoothly and i had no problems. after about 5-10 hours of break-in. i noticed that when i reved it to high rpms i had a vibration. i never really noticed this becuase i always kept the rpms low for proper break-in. so i made sure the balencer system was properly lined up with everything else(the balencer sytem is connected to the crankshaft through gears, and has marks on the gears to line them up properly), and it was line up fine. What could be the problem?

Answer
Hi Justin,

If all is correct, then the vibration, if not excessive, may be normal and you just did not notice it before. If you added weight like from a larger piston then the balance would be off.  I don't know how that would be corrected.  Maybe a part change on the balance system?  You probably just replaced the rings with oversize rings and in that case nothing should be that different.  That's about all I can think of.  I hope it helps.

Best,
Michael