The basic idea is to take a stock flywheel, cut in down on a lathe to an appropriate diameter, and drill it with a bolt pattern. This becomes the flange for a hand-start engine.
Then, a spool is machined from aluminum, with a center section of about 2-3/4" diameter, about 4" long overall, with a flange on each end (one with the bolt pattern of the prop, the other with the bolt pattern of the flange). There is a hole about 1-3/4" diameter through the middle, I am assuming for weight reduction. Caveat: I have not seen this, nor flown behind one, nor built one. This is just the information I have been able to find. I have also read that if the machining, especially the bolt circles, is not done accurately, the resulting offset can create a horrendous vibration and possibly break cranks or cases. Regards, RonB
