retard your ignition timing a little bit to eliminate this backfiring...
heavier weighted flywheels were available from kawasaki, but not cheap... ask your local kawasaki dealer..
1 KX500 ignition timing is not adjustable without modification due to fixed screw holes. Therefore it is impossible for a KX500's ignition to advance or retard whether on purpose by a mechanic of by accident. For other 2T motors with adjustable timing this diagnosis is relevant but not for a KX500 with an unmodified stator plate.
2 I have found no evidence whatsoever of various flywheel weights available through Kawasaki for any year KX500. All years of kx500 I have seen part schematics for show only one flywheel weight per year model. Post some part numbers / evidence or such flywheels should be assumed to not exist. Quick Side Note: It is possible that as Kawasaki made changes to the ignition system throughout the KX500 model year history that various flywheels compatible with certain years of ignition system may have different weights. The only way to know would be to weigh for instance a 1989-1991 flywheel vs 1992-2004 flywheel.
3 In case you missed this thread's first page, "The problem is a sheared flywheel key & damaged crank."
Not trying to be harsh. Just want to set straight what can be for future readers of this thread. Thanks for your input.
