When I do a rebuild for general yard/garden tractors, I recommend that the balance gears are replaced. For a hot rodded engine that may turn up to 4000 rpm or higher, I leave them out and rebalance the crankshaft to a reciprocating balance factor that the gears contributed. This offers potentially better reliability, simplicity, and a small reduction in friction.
(Message edited by dkirk on March 14, 2006)
(Message edited by dkirk on March 14, 2006)