ORIGINAL: flhyr
how do you tell if its detonating? does it do something specific that screams detonation? maybe I just don't know what to look for.
In an extreme case you can hear the motor knocking or "pinging," but more often than not it will just overheat like in your case.
Here's another thing....you rebuilt the engine? Did you do a leak-test when you got done putting it back together? If there is exhuast gases escaping through any kind of gap in between the plug and the cylinder head, or the cylinder head and the sleeve.....it will get hot in a hurry.
Did you ever run a full tank of fuel through the motor on the ground at full throttle?