Kawasaki FB460v Backfiring ??

Discussion in 'Mechanic and Repair' started by mrg747, Jul 16, 2005.

  1. mrg747

    mrg747 LawnSite Member
    Posts: 2

    Greetings all. I have a 1988 Johns Deere with a Kawasaki FB460v 12.5 hp. The engine will not start and I here a backfiring noise coming from the air intake while cranking. Prior to this the engine was running fine. Could the timing be off or is something out of adjustment. I guess I need a starting point to fix this problem. Any input would be greatly appreciated..Mike
     
  2. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,022

    Well backfiring through the intake sounds like a valve not closing all the way.
    Being a older unit I believe I would remove the head and check for carbon deposits under the intake valve, It's very possible a piece broke loose and got under that valve.
     
  3. Wolf Creek

    Wolf Creek LawnSite Member
    Posts: 9

    Also check the flywheel key, it may have sheared or partially sheared off, throwing off the timing.
     
  4. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,022

    I didn't consider the flywheel key because it was running just fine when parked, But I guess anything is possible.
     
  5. mrg747

    mrg747 LawnSite Member
    Posts: 2

    Thanks for the replies. I also noticed that the engine seems to have less compression. When I spin it by hand it is very easy, the electric start seems to crank it 1 1/2 times faster then before. Could this be related to the intake value not seating???
     
  6. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,022

    Most definitely, Perform the task as mentioned clean all carbon deposits from the head, Piston and valve area. Rotate the engine by hand until each valve is open and clean the seat area carefully, Re-assemble and it should start up.
    Put a light film of oil on the head bolt threads and install just snugging them first, Then start with the bolt above the spark plug and torque to 25 to 29 ft.lbs. then go to the bolt below the plug then continue in a crisscross pattern. There is a pattern but I can't attach it on this site,But I use this pattern all the time with no problems.
     

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