Dave,

I received the YS 80 and opened it up and took a look. Yep, I know why it's surging.

Main bearing is toast (rusted and worn), piston is scored (as if run lean), small fracture in the ring. I cleaned the carb and it was nice and clean. I pulled the regulator and it appeared to be OK.


The good news is I ordered a regulator so I could install it in the YS 80.


The bad news is: after looking at the motor, I'll order up a new YS 91

As always,

Thanks for your support

Scooterpilot