HI David:

For some strange reason Yamada uses 3.5MM socket head bolts on the 60 long stroke instead of the 4MM ones on the short stroke. It's hell trying to get he 3.5'd any way, Home Depot has the 4's. I just left my engine with a machine shop to drill and tap it to 4MM. The info you just gave me looks very interesting and will check it out. Thanks, Bill