CDI bad

Is there any way to tell if a CDI box is bad? I don't have the option of swapping out one short of buying a new or used one. My problem is that my '03 CRF450R won't start. I recently took the carb apart and cleaned it, put in new gas, new spark plug, changed the oil and put on a new air filter (all part of my spring start up). The last time I started it up was in September. I havent been able to start it however, so I checked the spark with a spark plug tester and it jumps at least a 1/4 inch- 1/2 inch gap. I checked all the wires and the coil for resistance, and they are all within spec. My compression is reading about 5kPa after about 10-12 kicks and the throttle open. My friend seems to think it's the CDI box, but after reading some posts, I'm leaning towards maybe bad valves. I bought the bike used 5 years ago and only ride trails in Ohio. I have never done a valve job on it.

Should I buy a new or used CDI box or opt to send it to a mechanic who can do the valves?

BTW, TT is such a great source for information on problems. I go to you guys whenever I have issues (brown nose alert!). Keep up the good work.

If you have spark you CDI box is good. Although you cleaned your carburetor, don't take that as absolute proof that the combustion chamber is getting a whiff of fuel. Pull your spark plug and pour a small thimble amount of fuel into the spark plug hole, then kick it several times. Next you can pull your valve cover and check your valve clearance. If it is tight valves, it will usually still bump start.

The last time I started it up was in September. I havent been able to start it however,

Id bet my bottom dollar the pilot jet is plugged solid.

Its been at least 7 months since you started the bike and I bet you left the gas on, or didnt drain the float bowl when you stored it.

Thanks a million guys.

I dumped a shot glass full of gas into the spark plug hole and kicked it a few times. Got a backfire, then after a few more kicks it started!!!!! :confused: It was going at full throttle and my idle screw must have been turned up way too high. I'm not sure if this was an issue as to why it wouldn't start or not.

Funny story though- I had disconnected the kill switch the other day when checking the wiring and I had no way to stop it, short of popping it in gear. Mind you, I was running at a very high idle!(pretty much full throttle speed)!!! I should take a picture of the skid mark on my garage floor, hehe.

Thank you guys again :thumbsup:

i have an after market fly wheel in my 05 crf 450r and it was rubing the two wires on the stader. i believe this led to damaging the cdi box.after grinding the two wire so the fly wheel no longer rubs after an hour of riding the new cdi box still got fried. can any body tell me why the timing is still jacked up? where is the electrical problem?

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