99'c40tlrx

[Trippgun]

Question for the experts,
The above motor runs well, no problem starting or at idle. The problem is when under load it has a minor break-up. It seems the longer it runs the more frequent the break-up occurs. Also, seems to only happen at 3/4 throttle or more. I have replaced the cdi box, all new fuel system, new coils. Compression is great and even on all 3 cylinders. Just doesn't want to run wide open, it tries then it will skip. Don't know what to do next. It seems to be electrical but I can't find it. Could it be Rectifier or Stator? I don't know, need help. Thanks

[99yam40]

What do you mean fuel system is all new, what did you replace?

The carbs have 2 different size main jets from factory, are you sure they went back into the correct carbs?

I had a problem about like this and I finally figured out a previous owner drilled out the jets, my guess he was trying to make a 50 out of it.
I could remove the cowling and silencer, run into the wind and it ran OK but with the wind it would not.

The service manual has a way to test charge and pulser coils with proper test equipment.
I am suprized you did not do some testing before replacing all those parts