I've done probably 8 of them. I found Ranger Fred's method to be the one I liked best.

The Phelon flywheels are much more out of balance than the Walbro ones.

You can not grind the aluminum with a stone. It has to be cut with a carbide cutter which often clogs and has to be cleared with an old scribe.

I found that the smaller air powered die grinders with a 1/4" collet to work best. I use a # A-11 cutter with a 1/4" shank. I bought all this stuff at Farm and Fleet and TSC stores at one time.

The grinder I liked was a Campbel Hausfeld made in China that was like $12.95 and lasted about as long as it took to clog up the flutes on the cutter. The red linen fiber vanes were worn out. And being Chinese, no replacements available. So I cut some large zip tie pieces to about the right length with side cutters for the vanes and cut with the die grinder to my heart's content. I always used the same cutter and it didn't wear out on the diecast metal of the flywheel.

I used a balancer much like the Dubro called a High Point that is sold by B & B or Bennett Built. I mounted the flywheel on the arbor the same as talked about in the previous post.

I bought a larger more expensive die grinder but it wasn't handy for the flywheels