Honda TRX680FA Service Manual page 273

CRANKCASE/CRANKSHAFT/BALANCER
TROUBLESHOOTING
Excessive engine noise
• Worn or damaged connecting rod bearing
• Worn crankshaft main journal bearing
• Worn connecting rod small end
• Worn balancer bearing
• Worn, seized or chipped transmission gear
• Worn transmission bearings
Abnormal vibration
• Improper balancer timing
13-5