Kohler M16 engine higher rpm issue

dronedog

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i have a 42" GHS mower with a M16 Kohler engine. i bought the mower used and this engine did not come on this mower. the person i bought it from said they bought the engine with 20 hours on it. it may have been on a generator or anything originally as far as i know.

here is my issue:
the mower starts and runs fine up to a certain RPM. (do not have a tach i can use to see what that RPM is) it feels like it is a little over half throttle. i am trying to increase the rpm for cutting grass. but as i increase the throttle, the engine starts to stumble. it does not die but it just will not pick up the extra rpm.

if i add some choke, it dies all together. at first i thought it was not getting enough fuel. but i have tried to increase the rpm with the air breather off and you can see fuel mixture blowing out the carb. it also will spit some small drops of gas.

the carb on this engine is a Walbro WHG style with a fixed main jet. i have changed the needle valve on it to make sure it is not just leaking gas.

again my lower rpm and idle are fine.

is this a problem with fixed jet carbs? should i buy an adjustable one? don't want to waste a few hundred on a carb that won't help.

never had an engine that blew the fuel mixture out the carb. keep in mind it is still running while doing this.
 

dronedog

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think i figured out my problem. checked my valve lash today and the intake valve was about 1/4"... not .009. certainly the valve was not open very long in the cycle.

So i am adjusting the intake to .009. need to read up and see if there is a way to lock that adjustment or is it just the tension of the bolt in the lifter?
 

tom3

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Seems like some of the OHV small engines run forever without being touched, some need the valve adjusted every season, hard to figure. Glad you found the problem, you'll know where to look next time.
 
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