B&S 6.5 kicks back


Old 07-05-07, 08:46 AM
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Join Date: Jul 2007
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B&S 6.5 kicks back

Hi All
I have a 2002 Toro push mower with B&S 6.5 hp. All was working fine til other day when I tried to start . I would get a small back fire and starter rope would pull out my hand , all most took my hand off. this would happen when ever it would try to catch. I was thinking some how the timing was off. but can't under stand how this could happen
any info would help a lot thanks........... Will
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Old 07-05-07, 08:50 AM
msidan's Avatar
Join Date: Apr 2006
Location: Gouverneur
Posts: 289
This is indicative of a sheared flywheel key. Post your engine numbers and someone will give you a part number.

Sometimes this happens when you hit a rock or something.
Old 07-05-07, 01:08 PM
Join Date: Jul 2007
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not saying that the flywheel key is not sheared b/c i dont know much about it but i thought that the kickback is b/c of alot of compression.
Old 07-05-07, 02:21 PM
oldchevy4x4's Avatar
Join Date: May 2007
Location: TN
Posts: 96
Kickback can be associated with high compression, however backfire and kickback are generally caused by a sheared key.
You're correct in thinking the timing is off, that's what that key is there for.
Old 07-05-07, 03:45 PM
BFHFixit's Avatar
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Your problem does sound exactly like a sheared flywheel key. Should the crankshaft come to a sudden stop, the flywheel momentum can continue and shear the key. This actually cause the engine timing to advance, meaning the spark plug fires before the piston reaches the top of the stroke when ignition is supposed to happen, and pushes the piston back down and the crankshaft in the reverse direction.
Old 07-06-07, 02:14 PM
puey61's Avatar
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Location: Upstate New York
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The Briggs flywheel key is part number 222698S and the flywheel nut must be torqued to 55 foot pounds upon reassembly of the 'wheel. You mentioned, not, about striking a solid object with the blade but you must have. Be sure to check the condition of the blade as well as the crankshaft for straightness. If the crank is bent severely you may not want to procede any further since the mower will vibrate like the dickens and be unpleasant to operate, not to mention that the vibration will eventually rattle the mower apart.
Old 07-07-07, 01:26 PM
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Join Date: Jun 2007
Location: Monmouth
Posts: 29
It should be noted that the blade acts as a flywheel on many applications, so check also for a loose blade and/or a sheared blade adaptor key.

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