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Briggs engie trouble

D

Dorfi2

Member
My b@s 6 hp engine had to have valves refaced after a peice broke off the intake manifold and jammed a valve open..This was done at a professional rebuilder..Now when i try to start it it jerks the rope out of your hand and after 3 or 4 pulls it hasthe flywheel key cut of... i have checked valve lash and now the cam to crank timing and all is smack on so what now ?? maybe someone can tell me why this engine is so fast in time.. THANK YOU
 
(quoted from post at 06:39:44 11/27/22) My b@s 6 hp engine had to have valves refaced after a peice broke off the intake manifold and jammed a valve open..This was done at a professional rebuilder..Now when i try to start it it jerks the rope out of your hand and after 3 or 4 pulls it hasthe flywheel key cut of... i have checked valve lash and now the cam to crank timing and all is smack on so what now ?? maybe someone can tell me why this engine is so fast in time.. THANK YOU
Click to expand...

What is the model number?

With many Briggs engines you rotate the crankshaft past TDC so that the piston drops a specified distance, and THEN set the valves.

If the specific directions are not followed exactly the Automatic Compression Release will not be functional and the engine will act as you describe.

Are you following the exact manufacturer's procedure for your engine.
 
Makes me wonder if the flywheel is tightening down on the taper as it should. Would take more than a kick back to shear the key.
 
What does it power? Is it reinstalled back on the equipment? Many vertical crank engine for mowers as an example use a lighter flywheel as specified by the machine manufacturers. So the reaction of rope starting an engine like this commonly is what you are describing. This may also apply to chipper engines and maybe even generator versions.
Edit to add: So with the lighter flywheel the engine relies on the additional inertia of the mower blade as an example.

This post was edited by used red MN on 11/27/2022 at 07:26 am.
 
If it as much as shows a mark on the key,that's enough to knock it out of time ALWAYS replace the key !!!!!!!!!!!!!!!!!!!!!!!!!
 
They call them B&S for one reason. You tie a rope on them and throw them overboard for a boat anchor while fishing then cut the rope when done.
 
If it were in my shop, I would check the valve clearance again.

When you checked the cam/crank timing, how did you check? Did you remove the side cover (or sump) and while open, confirm the compression release on the cam was intact and working?

If it is regularly shearing flywheel keys either the flywheel nut is not tight enough or else the engine is out of time. (firing too early.)

There is the possibility that the ignition coil is firing too early. Not likely on a properly gapped module, however. (I see this sometimes on chainsaws, not on Briggs engines.)

Another thought is I am thinking some of those small Briggs engines used a cam with a plastic gear. I recall working on one for some time before I figured out that the cam was almost 180 degrees out of time. It was missing three teeth on one side of the gear.
 
Is it an over head valve engine?? If it is the valves are not set correctly and I'd be taking it back to the shop and have them fix it correctly. The overhead valve engines have a compression relief that is set by having the valves set correctly
 
What Mark and OldSarge said. Just a mark on the key advances the timing a lot. A partially sheard key reeeealy advances the timing so much that it will hurt your hand when you start it. Also like others have said, is the flywheel tight and are the valves set properly.
 
(quoted from post at 06:39:44 11/27/22) My b@s 6 hp engine had to have valves refaced after a peice broke off the intake manifold and jammed a valve open..This was done at a professional rebuilder..Now when i try to start it it jerks the rope out of your hand and after 3 or 4 pulls it hasthe flywheel key cut of... i have checked valve lash and now the cam to crank timing and all is smack on so what now ?? maybe someone can tell me why this engine is so fast in time.. THANK YOU
Click to expand...

How about posting back with a model number and how you set the valves?

With the model number the valve setting procedure and be verified and the flywheel nut torque looked up.

One other thought, if the valve settings are, in fact, correct and the flywheel is properly torqued, I wonder if it's possible to mount the ''armature''/electronic ignition module to the block flipped over and if that would make for an early spark???
 
I read all the reply's and all are good things to check! I was wondering if You might have had the coil off and put in on backward ?It does make a difference. btdt !Roy
 
Cat guy, then what is your preference? A lot of back breaking jobs have been made easier by those engines. Are they a bit finicky at times and cause their share of problems? Yes, but all in all I do not think any of us would want to be without small gas engines. Next year when I want my lawn mowed I will call you up every week, I am sure I can find an old reel push mower you can push around to clip it off. Or the next time someone on here pours cement with a portable mixer, they will call you to man the crank.

This post was edited by used red MN on 11/27/2022 at 08:23 pm.
 
(quoted from post at 08:39:44 11/27/22) My b@s 6 hp engine had to have valves refaced after a peice broke off the intake manifold and jammed a valve open..This was done at a professional rebuilder..Now when i try to start it it jerks the rope out of your hand and after 3 or 4 pulls it hasthe flywheel key cut of... i have checked valve lash and now the cam to crank timing and all is smack on so what now ?? maybe someone can tell me why this engine is so fast in time.. THANK YOU
Click to expand...

The key is not there to keep the flywheel from slipping. It is there to time the flywheel.
If you are shearing the key, the flywheel nut is not tight enough, or there is damage to the shaft and/or the flywheel.
 
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