2005-2009 Honda TRX400EX/TRX400X Service Manual, Page 330Get this manual
21TROUBLESHOOTING
ENGINE DOES NOT START OR IS HARD TO START 21 -2 ENGINE LACKS POWER 21-3
POOR PERFORMANCE AT LOW AND IDLE SPEED 21-5 POOR PERFORMANCE AT HIGH SPEED 21-6 POOR HANDLlNG 21-6