1999-2004 Honda TRX400EX FourTrax Service Manual, Page 254Get this manual
TROUBLESHOOTING
ENGINE LACKS POWER
Possible cause
1Raise wheel off the ground and spin by hand
Wheels does not spin freely
Wheel spins freely
Brake dragging Worn or damaged wheel bearings Drive chain too tight
2Checktire pressure
Pressure low
b Faulty tire valve
Punctured tire
Pressure normal
3Accelerate rapidly low to
second Engine speed reduced when clutch is released
4Accelerate lightly
Engine speed doesn't change UClutch slippingWorn clutch discsplates accordingly when clutch is released Warped clutch discstplates Weak clutch springAdditive in engine oil
En ine speed increases
5Check ignition timing
Engine speed does not increase
Choke valve closed Clogged air cleanerRestricted fuel flowClogged muffler Restricted fuel tank breather tube