I just purchased a Ryobi 31cc short shaft & I am going to machine my own parts but I'm getting confused as how exactly the crank shaft adapto is supposed to work. One set of instruction talks about modifications to the stock flywheel nut but I can't figure out how to use that nut & install a extension with the prop hub adaptor. It seems like it would be easier to machine the flywheel nut, shaft extension, & prop hub adaptor into one piece. And if so, how long do you make the adaptor from the face of the flywheel to the back of the prop?

Anything more than about 2 inches is too long...The new hub just takes the place of the original nut....

I've read where guys have stripped out the aluminum hub when tightening the prop bolt. What do you think about a hub that would fit over the stock nut & would hub need to be locked somehow to the nut or would just the tension from the prop being bolted on be enough to hold the hub-spacer in place.

If you use 2024 or 7075 aluminum and a good tap that doesn't cut oversize there should be no problem with stripping the hole..If you start with a 5/16 you can always re tap to 3/8, then 7/16....Or helicoil the hole in the first place, stainless steel is pretty hard to strip...
The hub holds the flywheel on, a bolt in the hub holds the prop on.....Works well enough to be used on a Quadra 100cc, it should hold a wimpy little hub on a weedie ....Use Loctite, preferably green 638....
If you want to make a hub to fit over the nut you could copy a G38...The hub bolts to the flywheel with two 6mm Allens using tapped holes where the studs for the pull starter pawls were mounted...It's overkill on a small engine....12 lbs thrust is not gonna pull anything off...
To use a single bolt to hold both on you would have to drill and tap the end of the crank...Like a K&B glow motor...

Does anyone know where I can get high compresion rings for my two ring Ryobi? Thanks John L.

Well, I don't know what you mean by "high compression rings" but I get all my rings from Frank Bowman. They work super!!

AV8TOR

Frank Bowman
1211 N. Allen
Farmington, NM 87401
(505) 327-0696
[email protected]

What do Bowmans rings do for me that the stock rings wont?

Bowman rings = compression = power