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Discussion Starter · #1 ·
Working on a Cub cadet src-621 push mower with the kawasaki FJ180V 4 cycle engine. The needle and seat leaks (very slow) after an overnight sit. The next day you cannot turn the engine over (hydro lock) without removing the spark plug first. I installed a shut off valve and on each shutdown, I allow the engine to run maybe 30 seconds after closing the valve to burn some remaining fuel in the float bowl and everything is ok on the next day start. I removed the carburetor and try to blow into the fuel inlet with the carb upside down (to allow the float to push the seat closed) and it appears to allow air to bleed past. So I tear down the carb and find a little "ring" of wear on the needle jet. I had to get out the magnifing glass to see it. To my surprise, Partstree and others tell me it is 17 bucks for a needle. Sheesh. There has to be another alternative or a cheaper part. It has a Walbro carburetor made in Japan. Says "LMJ" on the side of it. The part number is km-16009-2136. Can anybody help me out here? I really don't like to have that valve on there as a fix. Not very professional. Thanks in advance.
 

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Discussion Starter · #3 ·
Thanks for the information. I could not find the exact carburetor on that site as well as others and even the models that were close, the picture wasn't in agreement with what I have, although, the needle part did LOOK the same and it was less than 3 bucks. Hmm, a call to my local CC dealer says they sell them all the time and currently are out of stock but he can get one for about 12 bucks and have it on Monday afternoon.
 

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did you check the float. i had a carberayor which developed the same sympthoms. had a small pin hole. just remove and shake to check. good luck.
 

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Discussion Starter · #6 ·
Installed the needle, bowl gasket and intake gasket today. She fired right up as usual but not with the usual few seconds of a rich roll. Ran it till it got warm and changed the oil. Let it run till it got good and hot. Fired right up after a 6 minute hot soak. Then another run and a 30 minute hot soak. ran great. So now I will let it sit all night and see if it starts good and no more hydro lock tomorrow morning. Update tomorrow.
 

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Discussion Starter · #7 ·
After an overnight soak it still hydro locked. But with about 80% less fuel in the cylinder when I pulled the spark plug to inspect. The only thing left could be the brass seat in the aluminum bore has corroded (galvanic corrosion) and it is leaking by there. I am not investing in a new carburetor for this machine. Installing a shut off valve for now. I can't believe someone else hasn't run into this same problem with kawasaki engines with the Japanese Walbro aluminum carburetor.
 

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One trick a motorcycle mechanic friend of mine does every now and then is take a really small piece of really fine steel wool and put it on the end of a Q tip. He pushes that into the seat and lightly spins it around. It polishes the seat a bit and most the time takes care of the crud and corrosion that happens up in there. Clean it out real well with carb or parts cleaner afterwards.
 

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Discussion Starter · #9 ·
Just purchased another cub cadet SRC621, Kawasaki engine, with the exact same problem (filling the cylinder with fuel overnight). It has to be from either the primer bulb circuit is somehow allowing fuel to siphon OR the seat insert inside the carburetor body (needle seat) has corroded and allowing fuel to bypass the seat (which is pressed into the carb body), into the bowl, then overflow. Also I believe that the problem with these Kawasaki engines and head gaskets are partially because folks with an engine hydro locked with fuel, will do their best to turn the engine over and with the the hydo lock condition, the gasket is the weakest link next to the starter cord!
 

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Discussion Starter · #11 ·
I tried looking up a seat and I thought the path led to "replace carburetor body or carburetor".
 

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The LMJ does not appear to have a replaceable seat, just the LMT and LMS. I would try polishing the seat up a bit, although I would use tooth paste with a fine grit in it on a q-tip rather than steep wool. The steel wool could scratch the brass up too much if you got over aggressive.
 

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Discussion Starter · #14 ·
Thanks for all of the ideas. I will dig back into it again and give you my results.
 

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Discussion Starter · #15 ·
Polishing didn't work. I installed a fuel shut off valve and after each mowing job, I close the valve and let the engine run for a minute and release the bail. No more problems. I believe the pressed in brass seat is leaking around the aluminum bore in the carburetor. Rather than spend some serious cash for a carburetor, this 5 dollar valve works fine. **** corrosive ethanol fuels!
 

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Thanks for the update. Sorry you couldn't track down and repair the ailment. I have a couple myself that I have learned to live with for now ;)
 
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