FB460V Backfires.

[kh0432]

Picked up a John Deere SX95 with a Kawasaki FB460V. Mower has been sitting for over a year but the seller assured me it was running when parked. When I tried starting it with starting fluid it would cough from the carburetor and muffler. Could both valves be stuck from sitting? Haven't done a compression check yet because it's too cold to work outside. Just trying to get some ideas before spring. Thanks

 

[bertsmobile1]

Yes iif stored badly you can get enough rust on both valves to prevent then closing fully.

 

[kh0432]

I'll pull the valve cover off and see if they're moving freely while cranking. Maybe spraying the stems will free them up and I'll check the valve clearance while I'm in there.

 

[kh0432]

Got the motor running after cleaning the carburetor. Now it surges a lot at idle, not as bad at full throttle and when I engage the blade it smooths out and runs fine. Any thoughts?

 

[Hammermechanicman]

The idle circuit on the carb still needs cleaned. When you engage the blades you load the engine enough to run on the high speed circuit.

 

[StarTech]

Pay extra attention to the pilot jet area when cleaning too.

 

[kh0432]

Cleaned the carb twice with 2+2 then bought a Ultrasonic cleaner and ran it through 2 - 4 minute heated cycles with detergent. This thing is squeaky clean and still doing the same thing. Runs great under a load. I have a new carb coming today and will put it on tomorrow and post the results. Thanks for all the input.

 

[Hammermechanicman]

The idle circuit is the smallest passages in the carb. If it surges on the govenor the idle passage is blocked. Get a set of acetylene torch tip cleaners and ream out all the idle passages. If it has a Honda type pilot jet the passage will be tiny.

 

[StarTech]

two 4 minutes cycle is no where enough time as it take 1-3 30 minutes cylces on the USC I got here that has four 40watts ultrasonic transducers to clean many carburetors deeply especially the dirty ones. Just because is clean on the outside doesn't mean it is cleaned in those tiny internal passages.

 

[bertsmobile1]

two 4 minutes cycle is no where enough time as it take 1-3 30 minutes cylces on the USC I got here that has four 40watts ultrasonic transducers to clean many carburetors deeply especially the dirty ones. Just because is clean on the outside doesn't mean it is cleaned in those tiny internal passages.

Same here.
Cube carbs get a degreaser soak the rinse to remove the external crud.
If it is set up I might give them a soda blast instead, depend how grubby I am as the soda goes everywhere.
For large carbs, they get an external soda blast then disassembled and another soda blast followed by at least 1 x 30 minute ultrasound using a special carb formula I get from my mower parts wholesaler.
After that they get a seecond 30 minutes using a 5% white vinegar solution
after that it is a final rinse in near boiling water.

Takes a long time, but the machine does the work while I do other things.