Seen bad plug caps cause those symptoms . Either carboned up on the plug connection, or poor connection where the cap screws onto the wire, or a burnt out resistor.

 

I checked plug cap its reading 5k and I've got continuity through the wire so connections are good.

 

i once had a bad spark plug causing problems as rpm got higher (was a new plug even)

 

Well got new coil and plug cap on order so it's a wait and see what happens.

 

Found out what was causing my engine stumble. I had changed the headlight to an H4 led bulb and thought well I've tried everything else. So I disconnected the light took it for a run down the street and no engine surge or stumble. I put the old stock bulb back in and it runs like a champ. I switched between the two bulbs a few times just to make sure the problem did repeat itself and the led is definitely the source. I called tech support for the company I bought it from and explained the issue, of coarse they've never heard of one causing a problem like this. They didn't deny that it wasn't plausible either and hat's off to tech support are going to help getting it resolved.

 

NEVER would have expected that! Good catch.

Ride on
Brewster

 

Tech support called me earlier this afternoon and they've already got a replacement in the mail. I'm impressed with their customer service. Probably have on Monday so we'll see if it repeats itself.

 

So surprising!... I guess that LED bulb has switching electronics to regulate the led current, resulting in switching spikes that couples into the crankshaft sensor circuit. Said coupling might occur only with a defective led electronics or a missing ground in the harness.

I'm eager to see how your bike runs with the replacement bulb, keep us informed!

 

I'm thinking there might be an issue with the PWM controller. Maybe it wasn't shielded properly. When I get the new light I'll be sure and post the results.