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Discussion in 'Lawn Mowing' started by Dingo, Mar 21, 2000.

  1. Dingo

    Dingo LawnSite Member
    from TN
    Posts: 133

    i just bought a new mower and it backfires everytime i shut it off. Its a exmark 19kaw. anybody have this problem too? What should i do about it?
  2. Guido

    Guido LawnSite Silver Member
    Posts: 2,085

    I had the same problem with my 14hp Kai on a 93 exmark 48&quot; Never did figure out what caused it though..??? Sorry!!<p>----------<br>&quot;guido&quot;<br>David M. Famiglietti
  3. sparkspride

    sparkspride LawnSite Member
    Posts: 2

    I have had these problems with kohler motors also. The reason is the piston clearance is a few thousands less than most of the older mowers. Fact: Make sure that you idle your mower down all the way before you shut it off. If you don't there is a chance that you could over torque your rod and have to have a rebuild job that could happen everytime you shut your mower off. These high compresion motors really need to be idled down. It will save your motor
  4. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    In addition to what Sparkspride wrote you should also allow the engine to idle for a minute or two before shutting it off.
  5. DMC300

    DMC300 LawnSite Senior Member
    Posts: 325

  6. Green Acres

    Green Acres LawnSite Senior Member
    Posts: 316

    You should let every piece of equipment idle for a few minutes before shutting them off. It's kinda like when a human runs a mile they say it's good to walk for 10 minutes afterwards to let your body cool down. Hope this will fix your problem.
  7. DTM65

    DTM65 LawnSite Member
    Posts: 52

    I read in the Kohler manual that for engines that are not equipped with a shutdown solenoid, you have to let them idle before you shutdown to avoid the backfire problem. <p>Some engines have them, some don't.<br><p>----------<br>D. Tom<br>
  8. farmall

    farmall LawnSite Member
    Posts: 13

    The reason the engines backfire is this. In order to help the engines to keep from running lean and burning pistons or valves, they run a little rich in the fuel mixture. When you let them idle, this extra gas builds up in the muffler and when you shut the engine off, there is actually a heat soak for about 20 seconds. This means that the muffler gets hotter after you shut the engine off, than when it was running. It gets hot enough to autoignite the fuel mixture, thus causing a backfire. I believe the exmark manual recommends shutting them off from half throttle to alleviate this problem. This richens the mixture in the muffler enough that there is not enough oxygen in the mixture to autoignite. No backfire. The backfire should not cause any problems inside the engine, since this all happens in the muffler.<p>hope this can clear some confusion up<br>
  9. Evan528

    Evan528 LawnSite Silver Member
    Posts: 2,144

    all of my kawisakis and kohlors backfire if i dont let them idle for a minute or so. im very impatient doing this but if i dont my 25hpkohlor will backfire so loud it sounds like a car exploded!
  10. Bobby

    Bobby LawnSite Senior Member
    Posts: 258

    I had the same problem wit my 25-Kohler.The distributor advised me to shut it down at half throttle. It works.I had a 14-Kohler that blew up three mufflers. The third one cost 140.00 with the (special mounting kit.) They were under warranty. <p>----------<br>Bobby <br>Ft Lauderdale<br>

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