Hi Edwin,

I think you are correct that the long shaft is generally preferable as it likely allows for a range of fore/aft adjustment of the prop. The short shaft uses a prop hub and thus the prop location is fixed. Fortunately for the Cub, the prop hub is an ideal length. There may be other advantages to the long shaft that I don't know about.

I did the conversion for my first trimmer motor making the hub, hub nut, velocity stack and even the exhaust stack from solid aluminum but the Ryobi I bought from another flyer and he'd all ready bought the conversion parts. The motor has never been run... but I don't know where he got it from.

The one other thing that I might note... the mount that I have has mounting flanges that turn out where many of the mounts are made from rectangular tubing and therefore have no outward flanges and bolt through the area aft of the carb. With the set back firewall, the longerons and deck will be 2" forward of the firewall making it impossible to get at all four mounting screws. Studs would need be fixed to such a mount and nuts used aft of the firewall and as I can't yet visualize the interior after the firwall move, I'm not sure that would be fun. I'd think that an outward flanged mount would be a better choice. The flanges will need to be on the sides... as the mount will set fairly close to the upper deck.