Q&A Lower end check
Cam
Tool in place ready to cut center cam bearing surface to correct size
after the two sides of case are torqued to specs.
The dark lines in the main bearing saddles is where the oil flows around the main bearings. This area does not wear. If you run your fingernail over this surface and can catch you nail on the dark ridge, then its time to have the case align bored. The Main bearing flange next to the flywheel must fit snugly, as this bearing controls the crank thrust. (.003" / .006")