I have a Tecumseh ohv155 204502a
The piston has a arrow next to the piston retaining pin
Should it face the fly wheel

If the piston has fly cuts, the arrow points in the direction of the fly cut and valve side so the valves don't hit the piston. It may be front or back. This is for a 4 cycle. In a 2 cycle, usually points in the direction of the exhaust flow, toward the exhaust port on the sleeve.

If the piston has fly cuts, the arrow points in the direction of the fly cut and valve side so the valves don't hit the piston. It may be front or back. This is for a 4 cycle. In a 2 cycle, usually points in the direction of the exhaust flow, toward the exhaust port on the sleeve.it's a four cycle

Align the piston so the flycuts are on the valve side.