Symptoms of a faulty pressure relief system on K301 Kohler

Gearjammer

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I'm trying to get a donor motor started in a cub 126. Got spark at the plug. New carb that seems like it will work. Cranking the motor with spark plug out spins fine. Putting the plug in causes the motor to spin once and then quit. ( due to compression, I'm guessing) Battery seems good and so does s/g. Your thoughts, guesses, and observations welcomed and appreciated. Thanks. Gearjammer
 

cpurvis

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Compression release isn't working. 12 hp Kohler?
 

Gearjammer

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Thanks Cpurvis for the quick reply. It is a K301 Kohler 12 hp. Where, what's wrong?? How do I fix? Any way to by pass?
 

Romore

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Check your valve clearances, should be .010" on both. If tthe ACR has failed (unlikely) you need a new camshaft.
 

cpurvis

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Thanks Cpurvis for the quick reply. It is a K301 Kohler 12 hp. Where, what's wrong?? How do I fix? Any way to by pass?
As shown in the manual Rivets cited, the compression release is part of the camshaft assembly. This is a flathead engine and valve lash is not something that is easily adjusted. It could be something as simple as a broken spring on the compression release, but you'll have to perform an autopsy to find out. No way to bypass that I'm aware of.
 

ILENGINE

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As shown in the manual Rivets cited, the compression release is part of the camshaft assembly. This is a flathead engine and valve lash is not something that is easily adjusted. It could be something as simple as a broken spring on the compression release, but you'll have to perform an autopsy to find out. No way to bypass that I'm aware of.
The K301-341 should have adjustable tappets. And to the OP I don't think I ever came across a K series with a broken ACR. Could happen but rare.
 

cpurvis

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The K301-341 should have adjustable tappets. And to the OP I don't think I ever came across a K series with a broken ACR. Could happen but rare.
I guess we were just lucky because we had one of those 'rare' failures but on a 10 hp Kohler. I didn't say the valve lash wasn't adjustable, just that it is a PITA compared to an OHV engine.
 

ILENGINE

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I guess we were just lucky because we had one of those 'rare' failures but on a 10 hp Kohler. I didn't say the valve lash wasn't adjustable, just that it is a PITA compared to an OHV engine.
Compared to the OHV engine they are a pain. Just with the adjustable tappets don't have to remove the head and remove the valves to grind the stems. After thinking about it I may have seen one about 10 years ago, but the issue wasn't that it didn't open to release the compression, it was stuck in the operating position so wouldn't deactivate causing engine backfire.
 
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