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post #1 of 7 Old 06-11-2011, 01:40 AM Thread Starter
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B&S keeps breaking flywheel key??????

Hi all,
I have a Craftsman riding mower with a 16.5 horse Briggs and Stratton 31H777-0202-E1 030215za engine on it.

It broke a rod which we have replaced, everyting else looks good.

Problem is, now it keeps breaking the flywheel key. We thought maybe it was the valves but they have been adjusted and the key still breaks.

What could this be? The torque on the flywheel nut? How tight should it be? Or is there something else that could likely cause this?

Thanks in advance,
Dan
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post #2 of 7 Old 06-11-2011, 07:37 AM
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Re: B&S keeps breaking flywheel key??????

Flywheel Nut torque spec is 100 ft/lbs. Make sure the crank and the flywheel taper are clean and dry.
Dave
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post #3 of 7 Old 06-11-2011, 08:33 AM
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Re: B&S keeps breaking flywheel key??????

They shear pretty fast if they are not torqued down enough
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post #4 of 7 Old 06-11-2011, 09:47 AM
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Re: B&S keeps breaking flywheel key??????

Quote:
Originally Posted by DLF_IN View Post
Flywheel Nut torque spec is 100 ft/lbs. Make sure the crank and the flywheel taper are clean and dry.
Dave
Many people make the mistake of thinking that the key is supposed to hold the flywheel from moving on the crankshaft. It is ONLY for positioning the flywheel on the crankshaft, the proper torque on the taper is what holds the flywheel.

Walt Conner
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post #5 of 7 Old 06-11-2011, 07:46 PM
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Re: B&S keeps breaking flywheel key??????

If the nut torque is correct, you might want to lap the crank and flywheel together to make sure they are making good contact.

Remember, I'm pullin' for ya! We're all in this together!
(Red Green)

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2006 Conquest, 54" deck, Vanguard engine
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post #6 of 7 Old 06-12-2011, 03:32 AM Thread Starter
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Now it will only run full throttle?

Thanks all, we tightened the flywheel and now it's not breaking the key, HOWEVER, for some odd reason it only will run at close to full throttle.
My friend and shade tree mechanic is working on it but is stumped.
According to him all the linkages to the throttle, governor etc etc look good.
What gives?

Thanks again!
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post #7 of 7 Old 06-12-2011, 11:44 AM
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Re: B&S keeps breaking flywheel key??????

Have you tried running it with the choke partially closed? If it runs better, it's running lean. Try closing the choke varying amounts, see what happens.

Remember, I'm pullin' for ya! We're all in this together!
(Red Green)

Living in The Land Of The Free - because of The Brave!

2006 Conquest, 54" deck, Vanguard engine
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