2004-2006 Kawasaki 900 STX Jet Ski Service Manual, Page 109Get this manual
8-12 ENGINE BOTTOM END Crankshaft Maintenance
The crankshaft changes the reciprocating motion of the piston into rotating motion to drive the jet pumpCrankshaft trouble, such as excessive play or runout, will multiply the stress caused by the intermittent force on the piston and will result in not only rapid crankshaft bearing wear, but also noise, power loss, vibration, and shortened engine lifeA defective crankshaft should always detected at an early stage and repaired immediatelyThe following explanation concerns the most common crankshaft problems and the method for measuring play, runout and con-rod alignmentIt does not cover crankshaft disassembly because of the highly specialized equipment that is requiredIf crankshaft components become damaged or worn, the entire crankshaft should be replaced as an assembly
Connecting Rod BendTwist