Slipping Starter motor belt

[allenc3]

At the end of this build, but small things keep comonh up.

I am using the EZGO starter Generator with my Vegas 460. I have a ported and milled head on this clone along with an advance key.

When the motor is cold, the starter turns the motor with know problem, but when hot, the starter motor pulley slips. I have tightened this thing to the point of stitching the belt. It still slips.

When the stock engine, the tension-er was a treadled rod, and you could get it pretty tight, but the clone setup is just a bar/

You guys have any tricks to solve this issue? How about a cogged belt? would that slip too. Can the pulley itself be de-glazed or otherwise roughed up?

Claude in Green Cove Springs, Fl