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Small Engines (Lawn Mowers, etc.)/Choke off, runs a little, dies...



Bought a mid-70s Case garden tractor/mower with a Kohler K301 engine last winter.

When I was looking at it, the owner said it was cold blooded and we ran it only for a few minutes with the choke on and idling to test the mower deck and drive it back and forth a few feet. Bought it and came back a few days later with a trailer and picked it up. Again, with the choke on as it was only run for a few minutes. Did minor maintenance this Spring, fluid changes, etc.. plus fresh gas.

Tried to use it last week. With the choke on and full throttle it runs OK until I engage the mower than it loses power and misses. When I turn off the choke after a few minutes of warming up moving slowly to full throttle it speeds up for a few seconds, starts missing, maybe backfires once or twice and dies. Runs best at half choke but not great.

Learned my lesson about "buyer beware" with the "cold blooded" comment but like the tractor and would like to use it for mowing. Ideas on what is wrong with the carburetor/engine?


Go to the Kohler Engine website and download the service manual.  You really need the service manual.

K301   12hp   Horizontal shaft

Since it is a mid-70's it should have a points and condenser ignition system unless someone has converted it to a modern electronic system.

I would start by make sure the points and timing are correct.  After you know the ignition system is properly set then start with the fuel system.  Fuel pump, carb...

Since it is pretty old I would also check the valve clearance but I would not remove the can check the clearance per the manual...just use a drinking straw or something inserted in the spark plug hole to determine top-dead-center on the compression stroke...I've done this a lot.

With the ignition timed, valves checked and you still have the same issue then the problem is most like fuel related.

Have you removed, dis-assembled and cleaned the carb to see if performance improves?
Make sure you check the carburetor butterfly shaft...I have seen these wear over time and cause air leaks which can cause your problem.

Small Engines (Lawn Mowers, etc.)

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Eric A. Jones


Lawnmower Repair . Certified Master Service Technician from B&S. Have 23 years experience on B&S, Lawn Chief, Weed Eater, Echo, Peerless, Wheel Horse, Snapper, Atlas, MTD, McCulloch, Homelite and many other numerous brands. Specialize in electrical repair.


Born and raised in the midwest. Started tinkering with engines when I was about 14 on my Suzuki RM-80. I began lawn mower repair at a small hardware store. I knew absolutely nothing. I read lots of repair manuals and met an older fellow who taught me many lessons. I continued working on small engines through high school and paid my way through college working on mowers at the same hardware store. Decided to get away from the midwest and mower repair so I joined the Air Force. I repaired air traffic control electronic equipment and ended up in Hawaii where I got a part time job at Small Engine Clinic. I gained a lot of experience from the Small Engine Clinic and had a blast repairing small engines. I then took the Briggs and Stratton Master Service Technician test and earned my MST. I then traveled to Wisconsin where I attended the factory update training seminar and received formal training. Continued working on mowers part time as I completed 20 years of military. Retired from the military on a Friday and continued in the lawn and garden industry the next Monday.

MAS Aerospace Operations BA Mathematics AAS Electronic Communications AAS Electronic Technology

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