why are plugs failing?

Discussion in 'Mechanic and Repair' started by rbig, Mar 10, 2005.

  1. rbig

    rbig LawnSite Member
    Messages: 112

    I've got several mowers with twin cyl engines, as well as a couple with single cyl engines. Seems like I frequently have plugs go bad.

    When I pull 'em and look at them, they show pretty normal, and no signs of heavy fouling like you'd expect to see with plugs that quit working. Cleaning the things doesn't seem to help. New plugs get me going again.

    What I do is keep a good supply of several changes of each kind of plugs I use on hand. Fortunately, plugs are relatively inexpensive, so it's more of an annoyance than a real problem.

    Has anyone else experienced this scenario? I've wondered what is causing the failures.
  2. rockytopp

    rockytopp LawnSite Member
    Messages: 120

    I do believe that as with many things in the repair work, the quality of control has gone out the window. I find this in auto parts as well. Seems that mexico and other parts that are imported are made to make the manufactur money and control is the last thing they care about. Parts that used to be rebuildable are now throw away, so the pride and care that once was standard has been lost. This is a sad situation but I am afraid here to stay.
  3. CCWKen

    CCWKen LawnSite Member
    Messages: 113

    You didn't say how long they're lasting. I replace plugs on the tractors twice a season. (Just started last week here.) The push mowers, trimmers and saws get a set per season. I could probably push the tractors to a set a season too but the power and economy take a real hit towards the end of the season. It's worth it, in fuel savings, to keep the engines running at peek power.

    The problems with small engines are heat and fuel delivery. Neither are controled very well and this takes a toll on spark plugs. Like you say, they are cheap but they can give a tired engine new pep in an instant. Sharp blades and new plugs save a lot of gas! When you go through about 50gal. a month, a 30-50% savings adds up in a hurry! Especially at $2.00 a gallon.
  4. sawman65

    sawman65 LawnSite Senior Member
    Messages: 754

    i bet you have kawasaki engines dont you???
  5. rbig

    rbig LawnSite Member
    Messages: 112

    Most of our engines that are having plug failures seemingly too often are Kawasaki
  6. LawnScapers of Dayton

    LawnScapers of Dayton LawnSite Silver Member
    Male, from Dayton, OH
    Messages: 2,572

    my Kawi's will foul plugs...especially in cool weather.......

  7. Guthrie&Co

    Guthrie&Co LawnSite Senior Member
    from nc
    Messages: 784

    i would check my fuel source. might want to try a diffrent fuel source
  8. Mower Man

    Mower Man LawnSite Member
    Messages: 100

    Kaw's coils aren't the best. Quietly, their upgrading.

    Choke settings MUST BE done as per the instructions using a 'set pin', and followed line by line.
    If not done as per instructions choke setting will be off.

    If using an "associated choke" thats when throttle & choke are combined...it's even more important.

    Recoil starts have been somewhat balky in cool-colder weather.
    Using a good 10-30W makes pulling easier....higher RPM which creates better coil induction....for higher voltage.

    Check oil for gas in it. When pulling over alot, and it doesn't start fuel can thin out the crankcase oil.
    Use the sniff test. If suspected.....carefully away from any fuel source, using a match-lighter stroke the dip stick. Stroke---not too much, not too close.
    If flame gets larger, or oil 'puff' ignites, there is fuel in the crankcase.

    Two starters are available.
    Standard torque & high torque.

    Standard uses a seperate starter solenoid NOT mounted (piggybacked) to the starter. Follow Positive (Red) cable from battery to a black colored object that has 3-4 terminals.
    Have seen these solenoids from water-moisture get inside---corrodes contacts which reduces electrical flow. R & R, coat terminals with dielectric grease after assembly, and use boots on BOTH terminals if they point straight up.

    High torque is usually a silver colored large round shaped Bendix style mounted on the starter. It provides about 200 more starting RPM.
    It's an option that costs alot more, so many mower companies don't spec it.

    Kawa's should have valve clearances checked as per Maintenance schedule. Very important to starting, and operational efficiency.

    Have seen fuel deposits (hard crystalline mustard color) form on the fuel bowl float jet, and metering jets.
    Sometimes using a engine fuel system cleaner helps.
    Sometimes only physically removing works.
  9. topsites

    topsites LawnSite Fanatic
    Messages: 21,653

    YEAH! I found out you need to make sure you get the special lawn-mower 2-cycle plug. In my case I was using automotive plugs made for cars which cross-referenced at the auto-parts store, and these things kept fouling.
    Make sure when you go to the auto-parts store, you tell them it's for a lawn-mower as the plug will cross-x to a car-plug when they look it up on the computer and that is wrong.

    Funny thing ... The auto-plug's thread and firing element is black while the 2-cycler is all silver in metal color.
  10. Teiman

    Teiman LawnSite Member
    Messages: 103

    Mower Man

    Thanks, just bought a used machine with a 23 Kaw FH
    (270 hrs) it blows tons of whiteish smoke for about 40 seconds
    on start up, smoke smells like fuel not oil. Choke off as soon as it fires, and
    the CC oil definitly stinks of fuel. Seems to burn clean after a minut or two.

    I think you gave the answer to my problem, No ?

Share This Page