The notch in the drive washer is something I wish YS had not taken out of production. When they went to a collet rather than a key to hold the driver on, it could not longer be marked that way.

As you pass TDC when turning the engine over, you feel the clearance on both sides of the rod. That's why we see some slop in the position of the driver notch. If you set the cam gear by turning the engine CCW as in normal rotation, it helps get the whole mess more correctly lined up. The notch is supposed to line up on the parting line of the crankcase mold.

At the service shop, they use a tool which aligns the crank at TDC, and then they drop the cam gear in before the rest of the internals are put in the engine. That way we don't worry about the rod slop coming into play.

Glad you understand. This can be kinda confusing.

Good Flying!

Dave