Cdi Box

[GYOGI65]

2000 400ex
started to act up would quit then start hard like advanced timing
checked starter ,checked valve adjustment,cam and cam timing
found short in tether kill eliminated this starts better but wii still quit at any time ,idle or full throttle just like key turned off may start back up or may not until sits for a while ,has white bros rev box ,not sure how old was on machine when bought ,rest of engine fresh ,new valves piston cam ,camchain and guides
now i am down to a guess so any help appreciated

[GPracer2500]

Unfortunately there's no way (AFAIK) to bench test a CDI. If you suspect the CDI is the troublesome component all you can do to confirm that is to test every other electrical compenent. If everything else checks out than the CDI can be identified as the problem by process of elimination. The only other way is to swap out the CDI with a known good CDI and see if the trouble dissapears.

CDIs don't fail often though. And when they do fail it's usually all or nothing--not sporadic. I'd keep looking for other shorted wires...

Have you checked the spark plug cap? They screw onto the plug wire and can sometimes corrode in that area causing erratic spark. Just an idea...

[DieselBoy]

Averell could a bad CDI (new stator) exhibit a trying-to-start symptom (turn over fires 1-2 times, stops, 1-2 times, stops.)?

[GPracer2500]

Originally posted by DieselBoy
Averell could a bad CDI (new stator) exhibit a trying-to-start symptom (turn over fires 1-2 times, stops, 1-2 times, stops.)?

Possibly--but I doubt it. I'd pull the spark plug and try and observe if the spark plug is actually sparking in an irregular manner that corresponds to the symptom you describe.