"Daniel J. Stern" wrote: First off, the engine could easily be rotated 1/4 turn with the spark plug in place by means of the pull-rope. There is no need to loosen and retighten the plug. Secondly, doing as you suggest will only worsen the damage to the flywheel and will very likely chew up the starter drive pinion as well.(clip) ^^^^^^^^^^^^^ Daniel, I hope I am not as dumb as I seem to you. This was my thinking: When you pull the rope, the compression generally causes it to stop in the same two spots, which is why there are usually two areas on the ring gear that go bad. If you stop pulling as the piston goes up on compression, it will rotate in reverse and stop. If you go past top-dead-center, it will rotate forward to another spot and stop. Those are the two particular spots you want to avoid to get around this problem.
When you put power to the starter motor, the pinion engages the flywheel before the engine starts to turn. Therefore, it seems to me the pinion would be fully engaged before the damaged teeth came around, so I would not expect the pinion to be damaged. The damage which usually occurs to the pinion in this situation comes from continuing to try to start when the ring-gear teeth have gone bad. Typically, you hear the gears grinding, and the motor does not turn.
Obvioiusly, the practical, sensible solution is to buy a new ring gear, as you say. But, as others have noted, many of us enjoy the challenge and sense of accomplishment in "outwitting" the system. You may not choose that for yourself, but I often do. (My family thinks I'm nuts. But they call on me when things need fixing, and that makes me feel useful.)