Whats the deal with the fire flame shooting out of my muffle

Discussion in 'Lawn Mowing' started by Dingo, May 24, 2000.

  1. Dingo

    Dingo LawnSite Member
    from TN
    Posts: 133

    Why does a flame shoot out of the pipe of my muffler when i shut it off. Its a new lazer Z? Is this something that will cause problems later? It also will backfire real loud sometimes. Is there something i should do to fix it?<br>thanks<br>Dingo<br>
     
  2. Guido

    Guido LawnSite Silver Member
    Posts: 2,085

    I'm no help at all when it comes to being a mechanic, but our Exmark 48&quot;'s with Kawi's do the same thing. (Big Bang and Fire show!) Our mechanic says, besides blowing apart the guts of the muffler, it won't do any harm. He told us piston and rings would do the trick, but ours are 10-15 years old. Yours, much newer, I wouldn't understand. Are your dealers any help or do they fit the description of &quot;the rest of them!!) Be carefull!!<br><p>----------<br>&quot;guido&quot;<br>David M. Famiglietti
     
  3. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    Just let the engine idle for a minute or so before shutting it off. When you drop RPMs from 3600 to idle a certain amount of unburned fuel will be in the muffler. If you shut the engine off without removing these unburned fuels the fuel continues to heat up until it ignites. It is also not the best thing in the world to shut the engine off without letting it cool down at idle anyway.
     
  4. Getmow

    Getmow LawnSite Senior Member
    from VA
    Posts: 445

    After letting it idle take it back to about half throttle then shut it off. That stoped it on my Kohlers.
     
  5. MOW ED

    MOW ED LawnSite Fanatic
    Posts: 5,028

    They stole your engine from the BATMOBILE :)
     
  6. Charles

    Charles Moderator Staff Member
    Posts: 7,866

    Just think of all that money you save on fireworks come the 4th of July
     
  7. John DiMartino

    John DiMartino LawnSite Silver Member
    Posts: 2,555

    Dingo-like the others here-I let my kohler idle for about 30 seconds to cool off the exhaust and valves before shutdown.The flame only happens when you shutdown and the throttle and rpms are about 1/2 and at least 2000rpms.As the engine spins to a stop,the mechanical governor tries to bring the rpms back up by opening the throttle,if the engine is spinning fast enough(wound up)at shutdown it will have time to draw a lot of fuel thru the engine,then it stalls.The muffler gets hotter immediately after shutdown,the fuel reaches flashpoint temp in the hot muffler and you have a flame.<p>----------<br>John D<br>
     
  8. Dingo

    Dingo LawnSite Member
    from TN
    Posts: 133

    thanks for the responses guys. Im glad i noticed this problem because i use to have my gas cans a litte off the side. now that would have been a real fireworks show.<br>thanks <br> Dingo
     
  9. grasscapeinc

    grasscapeinc LawnSite Member
    Posts: 175

    THat is a common problem. Throttle up to 1/2 to 3/4 when shutting off.
     
  10. Charles

    Charles Moderator Staff Member
    Posts: 7,866

    I put in mobile1 fully synthetic oil Kohler lazer after 135 hours of use. Didnt backfire at all in the first day of use with the new oil.hmmmm
     

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