This Is my first post so I hope I am doing this correctly. I have a 1988 Fourtrax TRX 300 that is burning out CDI boxes about every month to six weeks. Today it was running just fine and then just quit, checked and there is no spark to the plug again. It is not a big deal to change but I think the part is to expensive to have to replace every month or so. Anyone have any suggestion on what could be causing these CDI's to fail after such a short period of time. Aslo, from looking at the last one I replaced I assume there is no way to get inside them to just replace the bad resistor, electrode or whatever is going bad? Any suggestions would be greatly appreciated.

 

Is everything stock? No weird spark plugs? Aftermarket rev box?

Are you spinning the motor over with out the spark plug hooked up? The cdi needs a load, and having the spark plug hooked up and grounded is a load. If you spin over the motor, key on, and have no spark plug in the circuit...thatll screw up the cdi.

 

Everything is stock, use the ATV on the farm so no hotrodding or abuse. The engine was always running when the CDI quit, and the spark plugs came from the repair shop. Have never cranked the engine without the wire hooked to the spark plug in the engine or a plug that is grounded to the engine. Also, anybody know of an aftermarket place to buy a CDI? Hopefully at a more reasonable price that I paid the repair shop for the last one. I think it was $119. I am going to call the shop Tuesday but I assume that there is no warranty on theis part since it is electrical.

 

Im thinking its something downstream of the cdi, which has less resistance than it should is causing the burnout. Bare wire, shorted connector, or coil or spark plug wire. You can ohm check the coil and spark plug wire.

Try ebay for the cdi.

 

Checked the ohm resistance the last time the CDI went bad and everything checked normal. I will start checking wires for bare spots, and loose connections. Thanks for the help.

 

buy a new one fo sho