Small Engines (Lawn Mowers, etc.)/Kawasaki FC540V Throbs


QUESTION: I have a John Deere 265 with a 17HP Kawsaki FC540V engine in it.  I have replace the carburetor, but it still throbs when in warms up.  I runs fine till it warms up but than begans to throb.  It throbs the worst with the throttle in the middle postition.  This is the case when the valves are adjusted correctly to .006in.  I can adjust the fuel valve down till it quits throbbing but then you have to chock it when every time you start it and it dies if pull the throttle from fast idle to slow idly to quickly.

ANSWER: Did you check all the gaskets and seals around the carburetor?  

Is the Insulator Part Number: 16073-2097 warped and causing an air leak?

Did you perform a cylinder leak down test to make sure there are no leaks?

I once had a slightly loose head bolt cause surging...rare but the leak down tester clearly showed a leak.

I would use a file and check the insulator to make sure it is not warped.


---------- FOLLOW-UP ----------

QUESTION: Is a cylinder leak down test the same as a compression test?  I performed a compression test and was good.  I will try replacing the seals around the carburetor and the insulator(16073-2097) is broken so I will replace it.
Thanks so much for your help!

Leak down test uses compressed air, through the spark plug hole, to see how much air is leaking past the piston, rings and valves.  Different than a compression test; more accurate to determine exactly which part is leaking.

If the insulator is broken I'm betting it is contributing to the problem.


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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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