Yes - you have a woodruff key on the flywheel. If you backfire hard enough to "jerk" the engine the opposite way that it is spinning, the woodruff key can be sheared off. This prevents damage to the crankshaft because of the large rotating mass of weight the flywheel has. Because your crankshaft is pressed together, backfiring can also cause the crankshaft to twist out of alignment. This will cause major problems. I'd take a look at the source of the problem. Is it just backfiring after you have hot pipes, and shut down too quick. That will send tons of unburned fuel in to the hot pipes and cause a "pop." If so, let her idle down for a minute before hitting that kill switch.
This brings up a point that I would like to ask- in my opinion, it's never a good idea to shut any engine down after it's been run hard without giving it a chance to cooloff a little first by idling for a half a minute or so so the heat can dissipate. I ride with guys who run full-bore up a hill or something, and immediately shut their engine off as soon as they stop. Not good? Anybody agree?
most polarii that i have owned rev high after running then kick down to idle after a momemt I always wait for this lowering of rpm. and have never had a problem with backfire. I think I heard you can damage the fuel pump if you shut it off higher than idle. any one else hear this
I've heard that pumps take a beating from back-firing. And back-firing while accelerating will melt a piston in a few minutes.I've got the pistons to prove it, and you don't want to see them cuz they are ugly!
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