How to check if your CDI is fried??

[kc 300EX]

I might have fried the CDI on my KFX... how do I check it? I'm clueless when it comes to the electrical system. I had an electrician look at it and he said it could be fried, but didnt know how to check....... so how do you tell if its shot or not??

[foleyit]

Take the spark plug out and plug it back to the your spark plug wire, then ground the spark plug to the frame and when you hit your start button you should get a spark. If not, then I would bet that it's your CDI. That's what I did, I still had my doubts so I hooked up my buddy's CDI and it fired right up.

good luck!

[kc 300EX]

Fudge.... no spark:(

[wilkin250r]

If you ever perform this test, MAKE SURE YOU GROUND YOUR SPARK PLUG.

Not just because of the obvious reason that you won't see a spark, but because CDI stands for Capacitive Discharge Ignition. The capacitor MUST have a path to discharge, otherwise that charge just stays in the capacitor. Then the next spark comes around, and your CDI tries to stuff the capacitor full of charge again. Problem is, it's already got a charge on it.

If the capacitor cannot discharge, you run a very high risk of damage to your CDI.

[kc 300EX]

There's very good advice wilkin250r

I knew to do this because its the only way to check for spark (having it grounded) but I wasn't aware of the danger of not doing it. So thanks for pointing that out.

I'll be checkin out ebay for a new CDI, so if anyone happens to see one for a good price please let me know. Thanks a lot.

[boogiechile]

be careful if you use the frame for ground, a thick coat of powder coating is not too good of a conductor. Try using the engine case or cylinder instead. You may also want to make sure you are getting a signal to the CDI from the crank sensor before you buy a new CDI unit.

[kc 300EX]

Ok, the CDI doesnt look too healthy, the plug looks like it over heated and melted some. Its not that apparent, but the metal parts are greenish and look out of wack....... The plug on my wiring harness is the same way. Now what? Does this mean my wiring harness is shot too? How do I test to see if it is or not?
This information would probably be best to get from a manual, but I don't have one. Is it possible to get just the plug for the wiring harness? or is an entire harness the only route to go?

[kc 300EX]

ok, I just ordered a new CDI.. wheres the best place to get a wiring harness?