I bought this motor and got it tuned - up starts and runs fine for a few minutes. After about 6-7 minutes it slows down and then stops. I think it's overheating-it is aircooled. Any idea's would be appreciated.
Yessir...Sounds like a classic case of a failing coil or coils.
It is very common for a coil to function properly when cool,but short out and fail as it warms up.
Pull the flywheel,change coils,points and condensors.
You can get any of the parts that relate to the powerhead of that particular motor at any Tecumseh Dealer. Some of those also had water cooling on them to cool the exhaust side of things. I'm not sure where you get parts for the drive for them anymore. NAPA would be the first place I'd check.