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Small Engines (Lawn Mowers, etc.)/John Deere RX75 will not start


QUESTION: I have a JD RX75 with a Kawasaki 9hp engine It would not stay running after approx. 20 minutes and it would not start again until it cool down approx. 30 minutes later. It was suggested that I check the timing gears to make sure they were correct I checked and it was set right I did find signs that it had been taken apart before I put new gaskets on and cleaned it up with just shop towels no water or solvents after putting it back to together I can not get it to sun It back fires thru the carb. I have checked the fly wheel and it is OK not bent or worn the engine is a FC290V-AS0? something the last number is gone the serial number is FC290V-047192. I have put two new plugs in and it still will not start I have been told to replace the IGNITER but I am and sure about that the spark I am getting at the plug looks good lot of blue sparks coming off the plug in two places if it was the IGNITER I would not have any spark at all right? When it was running and then quit I have checked for spark and it was there and good. I am at that point now that blasting power is the next step. Please help or send any power you got. (just kidding)

ANSWER: Blue spark is good...should be working fine.

What are the vavle clearances set at?


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

QUESTION: .006 in. I forgot to tell you that I did lap the valves and then set the clearances at TDC I read something tonight that I should have turn the fly wheel a 1/4 turn and then set the clearances does that sound right? I have read so much and no two people are doing the same thing. I have worked on gas,diesel and race cars all my life and now I am getting my bu@%t kicked by a 9hp engine.

Briggs tells you to turn the piston 1/4 inch past TDC.  The Kawasaki manual states to adjust ate TDC when the engine is cold.  Clearance 0.006 inch for both valves.

Are you familiar with valve overlap?  All 4 cycle engine have valve overlap at TDC.  It may be very minor but it is a sure fire method to verify mechanical timing, i.e., the cam is properly timed.  Valve overlap can be very difficult to see but you can feel when both valves are slightly open as they will rotate in their seats.

Did you ever remove the ignition coil.  I doubt it is the issue but I have heard of people installing them upside down and affecting the ignition timing.


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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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