I have an 82 YT175 motor that came in a couple boxes. There is a 30mm spacer that was left on the head sided of the cylinder. The parts breakdown and gasket set only have a single gasket. The head doesn't look like it has been shaved. The only idea I can come up with is that the cylinder was shaved on the bottom to move the ports down and the spacer used on top to make up the difference. Any other ideas? The piston hasn't come yet. After I bore the cylinder and install the piston it might give me a better answer.