1999-2004 Honda TRX400EX FourTrax Service Manual, Page 233Get this manual
IGNITION SYSTEM
IGNITION COIL
REPLACEMENT
Remove the left side cover (page 2-31Disconnect the primary coil connectorRemove the spark plug cap from the plugRemove the two bolts, ground wire terminals and the ignition coil from the frameInstall new ignition coil in the reverse order of removal