I have a 2002 Honda 400ex that I bought w/no spark. So far I checked the ign. switch and kill switch continuity and they seem to operate properly. Bought a new coil, battery and rectifier and still no spark. Visually checked harness and grounds everything seems ok.I also got a used CDI off ebay. Im an automotive mechanic but cant figgure out this quad. Anyone know how to check elec. componets on this bike or any suggestions? Also where to find a wiring diagram? THanks

 

This may be too late, but a little trick I learned was to unscrew the plug cap, snip off 1/4 inch, and then rescrew on the cap. What happens occasionally is the wires in the cable break from the twisting/turning motion of taking the cap off the plug. It's worth a shot and doesn't cost anything...

 

Ive seen some cheap service manuals on ebay, there is a troubleshooting guide in them for finding out the defect. There is also a wiring diagram on the cd.
Have you ohmed the pick up coil , mounted by the stator? Do you get a neutral light? Fuse good?