I have a YS .53 that seems to run ok on high end, but every time I throttle back it dies and the carburetor is full of fuel, almost like there is an internal leak or something in the engine. The engine has endured a couple of crashes but I have sent it back to the YS repair station twice and they have fixed it both times. Any suggestions? thanks!

It probably got some dirt under the regulator valve, I'm in the process of resurrecting a .53 that needs the regulator rebuilt. You might try turning the regulator screw 1/8th turn CW and see if there is a change. Or take it apart and clean it.

I'll give that a try. thanks.