Did the increase in rpm come from the reduction of bearing area or from reduced weight (or a bit of both) ?

I was reading some old issues of Speed Times (the newsletter of the North American Speed Society control line stuff) and there was a note in one of the motor modification articles that you should demagnetize your crankshaft after you have finished working it over. Makes sense, any magnet in motion will induce a current in any nearby metal which in turn is power and in this case would be lost power as the rotating crank would have to overcome any back emf. A simple tape deck demagnetizer like those sold at Radio Shack should work.

I wonder how much difference it would actually make. It is one my list of things to try, magnetize a crank and then run a motor for a baseline, then demagnetize and run again within a half hour or so such that conditions dont't change much; and compar the results.

cheers, Graham