I have never (knock on wood) had a cdi fail. I have had 2 of the attached spark plug boots malfunction.(the origional boot has brass parts screwed into plastic, with a spring underneath.) eventually, you will pull off your sparkplug wire & the brass will be still on your plug. the spring will disappear and you'll be pedalling..... . Since then, I replace the ends with the automotive type first thing.
ya my brass peice and my spring fell out friday but luckyily i found them on my motor i just pulled off my spark plug cap and thay fell out but i put them back in and it works fine and my wires were being stupid but i fixed that. question is it normal that the spark plug cover is loose?
Also I'd like to add a warning (hopefully not too late for some).
With certain CDI units, it is sure death to pull the plug wire off and turn the engine over....I found this out by doing just that with a Kawaski powered aircraft. It smoked the CDI instantly.
ALWAYS MAKE SURE YOUR PLUG IS WELL GROUNDED TO THE ENGINE WHEN TURNING IT OVER.