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**K-B** · 09-12-2007, 04:01 AM

Another sign of a bent flywheel key is kicking back when you try to start it (the rope will violently jerk back).
Also, you will almost certainly need a new blade. Do not run it, even if the blade is just a little bent. You should also check or have the crankshaft checked for trueness, it will greatly decrease the engine life if it is bent. The easiest method of checking for trueness is first remove the spark plug, the remove the blade. Then screw in the blade bolt alone (It's best to have a new bolt for this test, but if you can't get one, just make sure the old bolt isn't bent). But just screw it in part way. Then have someone step on the handle and slowly pull the rope. If the crankshaft is bent, the bolt will not spin straight, but it will go in a crooked circle.
Tumbleweed, a bent crankshaft is actually quite a frequent problem, especially with the cheaper mowers (Briggs & Stratton engines). Those, for some reason don't shear a flywheel key very easily, the crankshaft tends to bend. (The do run like that, but they vibrate to pieces) The Hondas seem to be tougher, we had one in this spring where the guy had hit something, it had sheared off the blade retaining bolt and broken the blade adapter in half. The crankshaft was just very slightly bent. If that had been a Briggs, it would have been a total disaster.

09-12-2007, 04:01 AM	#4 (permalink)
K-B Moderator/Gearhead Join Date: Oct 2005 Location: NY Posts: 2,738 OS: Ubuntu 8.04 My System	Re: lawn mower ran over stump Another sign of a bent flywheel key is kicking back when you try to start it (the rope will violently jerk back). Also, you will almost certainly need a new blade. Do not run it, even if the blade is just a little bent. You should also check or have the crankshaft checked for trueness, it will greatly decrease the engine life if it is bent. The easiest method of checking for trueness is first remove the spark plug, the remove the blade. Then screw in the blade bolt alone (It's best to have a new bolt for this test, but if you can't get one, just make sure the old bolt isn't bent). But just screw it in part way. Then have someone step on the handle and slowly pull the rope. If the crankshaft is bent, the bolt will not spin straight, but it will go in a crooked circle. Tumbleweed, a bent crankshaft is actually quite a frequent problem, especially with the cheaper mowers (Briggs & Stratton engines). Those, for some reason don't shear a flywheel key very easily, the crankshaft tends to bend. (The do run like that, but they vibrate to pieces) The Hondas seem to be tougher, we had one in this spring where the guy had hit something, it had sheared off the blade retaining bolt and broken the blade adapter in half. The crankshaft was just very slightly bent. If that had been a Briggs, it would have been a total disaster. __________________ Registered Linux User #435503 Don't let socialists take over this country. Vote Nobama 2008!