[Planefixer4]

I’m also having a similar issue.....I have a DAYTONA tachometer on mine. My YSR seems to do this whenI do a hard run up to top-speed ( around 50 mph..not happy with 50mph at all ) . It seems like I’m losing ignition or starving for fuel. But once slow for a bit it goes back to running ok. I happened to notice that when mine starts doing the “cutting out” , my needle starts drifting towards zero RPM as if its not firing. Maybe this is a clue.

YSR, GT80 motor, Calamari pipe, 20mm Mikuni round-slide.

 

[Planefixer4]

OK....so, I had a spare YSR50 motor the guy gave me with the bike. I removed the flywheel and swapped out the whole stator. PROBLEM FIXED. Apparently, even though the source coil OHM checked good on the bench it fails when running.

REPEAT.....BAD SOURCE COIL CAUSES THIS PROBLEM