Vintage Dirt Bike Q & A

I can use your help, please.
I'm having a problem with my 79 CR250R. It starts and runs fine except for top end, under load, It breaks up and loses power. I am running the stock Keihin carb and started with stock settings. I have tried rejetting with no noticable improvements. Spark plug is still wet after a hard run. The engine is new, but I admit I haven't done a leak down test (don't have the test equipment). I am now suspecting the ignition. The spark looks week to me compared to modern bikes. I replace coil with an after market one. The grounding path on CDI and coil are good. Is there a way I can check the CDI unit? What else can I look for? In another post, I read people talking about CDI letters matching the side case. Can someone explain this to me in more detail? Since I have a couple CDI's; maybe I put the wrong one on?
This is getting fustrating, so all the help I can get would be appreciated
Thanks again,

Rick

Letters are stamped on the CDI box between the mounting holes, on the back side of the rotor, and on the square tab on the edge of the rotor cover. All should be matching with a letter A though F. Go to the Reference section and download the manual. It has electrical specs for all ignition components that you can test.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF