1986 Honda TRX250R Fourtrax.

Was running poorly above ½ throttle. Cutting out. Runs okay at 1/8 to ½ throttle.

The bike is hard too start. I thought the problem was in the carburetor, but after going through the carb I checked the bike for spark. The spark was weak (small and yellow). [I checked for spark in a dark shop, so not to have the lighting drown out the spark]. I could get the bike to backfire, but that was all. Here are the parts that I checked:

1. Pick up coil - in spec at 118 Ohms
2. Primary winding of coil - 0.4 Ohms (do not know spec)
3. Secondary winding of coil - 1.4 Ohms (do not know spec)
4. Stator - visually looked okay
5. Flywheel - visually looked okay (none of the magnets went bad).

I also replaced the following:

1. Stator
2. Flywheel

The only part that I do not have to replace the CDI unit/(black box).

Has anyone else had a experienced this?

Meantime I am trying to find a (known good) CDI to borrow.

Any help is greatly appreciated,

Thanks,
John

P.S. How do you check the output of the stator. Is it suppose to be 12VDC?

 

Yes, a poor cdi can cause a weak spark.

 

Thanks for the reply Red. Last night I won an auction on eBay for CDI unit. I hope this resolves the problem.

Thanks,
John

 

Sorry I took so long in posting my findings.

The problem was a weak/interminent grounding of the aftermarket kill switch.

Disconnected the kill switch and the bike runs great.

Thanks,
John