2006 Honda TRX680 Rincon Factory Service Manual, Page 518Get this manual
IGNITION SYSTEM
TROUBLESHOOTING
Inspect the following before diagnosing the system:Faulty spark plugLoose spark plug cap or spark plug wire connectionWater got into the spark plug cap (leaking the ignition coil secondary voltage)
No spark at spark plug
Ignition coil primary voltage UNUSUAL CONDITION Low peak voltagePROBABLE CAUSE! (Check in numerical order)