Originally Posted by
aspeed
I was going to make some cranks, but then got one of those Foras and kind of forgot about the Picco. The Fora can't use an rc carb, so it is sitting for a while till I can fly faster?!! I believe the Picco was a fairly expensive engine, but they were selling them off cheap ($30) because of the weak crank. I think there isn't enough meat left because the hole is too big for the bearing size used. If you make a smaller hole on a new crank, it will go slower, so the trick is to either use a bigger bearing size, bore out the crankcase, make a sleeve for the crank, or make a new crank for a bigger bearing and bore the case..........
I think MJD said his Profi uses the crankshaft as the inner bearing surface, so that frees up space to design a stronger crank and still have a big air passage. the downside would be hardening the crank to act as a bearing surface..I do not know what the complications are with that.
My Ford 8.8 rear end uses the same idea. The entire axle isn't surface treated, just the area where the bearings ride.