ORIGINAL: BillS
Inspect and clean.
Received a Tower .75 engine last week. The engine had a bind and didn’t turn through top dead center. Disassembled the engine and it appeared to have lapping compound on the piston. Burs were also found the on the sleeve at the top.
Although not a lot of trouble to fix the engine should not be run without inspection and cleaning and in this case fitting the piston.
One might guess that lapping compound was to assist in quicker break in.
Bill
A glow engine is supposed to be tight in top dead center. The difference between a loose engine may be as much as 10% top hp and low end torque.
The running in sequence will take care of that tight fit, but after running in, it still should be tight and stuck if left in top dead center for an hour or so.