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Cause/Fix for Backfiring??? (Kawi 31 Carb - 160 hours)

Discussion in 'Mechanic and Repair' started by Derwood, Nov 15, 2017.

  1. Derwood

    Derwood LawnSite Senior Member
    Messages: 893

    I have a 2016 Cheetah with a 31 Kawi (carb) on it. I dropped it off at the dealer for some warranty work, and to have the backfiring checked out. I just assumed the valves needed to be adjusted - quick fix and back home with it a couple days later. When I called today, he said he was talking to Kawi reps about a couple of possible causes and solutions. I'm in no hurry to get it back as the season (for me anyway) is over - I just can't put my trailer away until I get it home and cleaned up. So I'm not dealer bashing by any means. I like my dealer and the guys who work on my machine - I told him no rush at all.

    Any idea what else would cause the backfiring? It usually happens after I complete an account. The faster the engine is running when I shut down, the louder the "bang." If I am idling as slow as it'll go, it sounds like when the dog farts on the coach. When I started it in the shed last winter, it sounded like Uncle Buck's car (not sure if anyone will get that reference lol :) but it otherwise ran perfectly all summer. I did use a lot of gas, but most on here seem to agree it's a guzzler, so I didn't think anything of that. Just curious to see if anyone has some insight.

    Thanks for any input!
     
  2. DXN1EL

    DXN1EL LawnSite Senior Member
    from TEXAS
    Messages: 722

    Most if not all engines will do that if you don't let them cool down. When I finish a big property I leave idling, grab the blower and blow the engine, hydros for a good 1 min or two.
    On smaller jobs 15 to 20 sec does the trick. Otherwise bang!!!!
     
    weeze likes this.
  3. Derwood

    Derwood LawnSite Senior Member
    Messages: 893

    Last cheetah I had with the same engine never backfired and the 37 kawi dfi b4 that never did either. Maybe I just got lucky with those?
     
  4. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,157

    One thing that could be causing yer issue is the anti-afterfire solenoid, commonly called the fuel solenoid. It may not be stopping the fuel flow to the main jet/nozzle when ya de-energize it ( shut down). I woulkd check and make sure the main jet etc. is screwed in tight also, could be leaking a tad.
     
    sjessen likes this.
  5. MWHC

    MWHC LawnSite Member
    from Wyoming
    Messages: 218

    I have a Kawasaki fh680v that behaves exactly like this. Runs fine under load but backfires and pops really bad when blades are not engaged. Have replaced coils, carb cleaned, adjusted valves without good results. (All done by the dealer). Would love to hear another solution. Engine has been maintained well too.
     
  6. Derwood

    Derwood LawnSite Senior Member
    Messages: 893

    I will post what the dealer tells me when I pick it up. Hoping it'll be a few days.
     
  7. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,157

    OK.
     
  8. Derwood

    Derwood LawnSite Senior Member
    Messages: 893

    Dealer said Kawi told him that I should be shutting down my engine at FULL THROTTLE! He said he adjusted the valves a little, but they were pretty much within specs already. He's gonna try to get her good and hot and then shut done and see if she bangs. Surprised to hear Kawi said that...but what do I know!
     
  9. weeze

    weeze LawnSite Fanatic
    Messages: 12,607

    that's not the usual practice. normally kawi says move the throttle to idle for 1min and then turn the mower off. my kawi only backfired maybe 2 times in 1200 hrs doing it that way.
     
    Breezmeister and hort101 like this.
  10. Derwood

    Derwood LawnSite Senior Member
    Messages: 893

    Mine will backfire trying to start it sometimes (like over the winter when it cranks for awhile)
     

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