Spark Arrestor

Discussion in 'Mechanic and Repair' started by Godfather, Oct 8, 2007.

  1. Godfather

    Godfather LawnSite Member
    Messages: 186

    My (trusted) dealer told me that if you take them out the cylinder, and exaust port will carbon up instead, is this true? He said that it may have something to do with backpressure. Any mechanic Know?
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    I believe your (trusted) dealer has that back-ward's, Leaving them in causes more back pressure (exhaust restriction) thus more carbon build-up.

    Get them out of the way and the exhaust moves out of the port quicker thus less carbon deposits.

    Disclaimer; I am no two stroke joke.
  3. Breezmeister

    Breezmeister LawnSite Bronze Member
    Male, from South Jersey
    Messages: 1,758

    FWIW, chances are you will never find a carboned up exhaust port on a chain saw because it is almost always run at WOT. Back pack blowers, on the other hand, even run at WOT will not carbon up the port most of the time, but I have found alot that because of the baffles in the muffler, will carbon up the muffler. Trimmers, because of the EPA rules have a much smaller exhaust port then what was on models 10 years ago for the same CC size. Along with the sound restrictions just like the blowers create more back pressure and because of there smaller size port will carbon up the port and eventually the muffler. The only reason a spark arrester is in the muffler is to stop a spark from coming out and starting a fire.
    Soooo unless you are in NW Georgia, you really don't need anything else clogging up the muffler and exhaust port. There just ain't nothing good on TV tonight ;)
    ericg likes this.
  4. johnp900

    johnp900 LawnSite Member
    Messages: 71

    Don't take them out. The spark arrestor is also the "check engine light" for a two cycle. Yes, if you take them out, then the carbon tends to build up at the exhaust ports, heat goes up & then the cylinder & piston trash. If the screen is carboning up excessively, then you have other issues that need to be addressed. A properly tuned & running engine just does not have carboning problems. Also, the screen is only about $1.50. That's pretty cheap insurance.
  5. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Messages: 2,248

    I hate to disagree, John, but I've serviced well over 500 Echo and Shindiawa 2 cycle products. I've seldom found an obstructed exhaust port on any product that had the screen removed. On the other hand I have found numerous pieces that had both carboned up screens AND exhaust ports. Restro is absolutely correct in his assessment. As the screen starts to build up with carbon there is no other place for it to go but into the muffler, exhaust port, ring(s) or piston dome. It never fails that the plug is well coated in carbon as well.

    Blocked screens and ports are almost always the result of imcomplete combustion.. The biggest contributor is running at lower RPMs, the second is improperly mixed fuel(too rich) and the third is improper high and low speed adjustments in the case of an adjustable carb.

  6. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    Get that screen out and be done with it! Free flowing exhaust is king! Heck the way your detune a racing Briggs engine is with an exhaust restricter. That's what your screen will do - restrict your power. Pull it out - the world will still spin.

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