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52" ExMark Lazer HP running bad - NEED HELP PLEASE

Discussion in 'Mechanic and Repair' started by statman, Aug 11, 2007.

  1. statman

    statman LawnSite Senior Member
    Messages: 268

    My mower has been surging all season and the mechanic at the dealer said there is no carbuerator rebuild kit avail. I think I have a 23 or 25HP Kohler. Now today I broke the throttle cable and got it replaced and now it is running very rough and losing power in tall grass. Also, it is blowing black smoke when I engage the blades.

    I'm guessing carbueration, but if there is no kit available what do I do, but a new carb?
  2. cborden

    cborden LawnSite Member
    from 46140
    Messages: 178

    I have a 25hp Kohler on a Scag Turf Tiger. It was doing the exact same thing you have mentioned. We messed with it for a year, had carb cleaned out twice. In the I got a new carb and this seams to have taken care of the problem.
  3. fitzg2md

    fitzg2md LawnSite Member
    Messages: 156

    If you find it is the carb, I have a spare carb in good condition from a kohler 23 model kc23s spec number 76513.

    I just ordered a new engine as my old engine cracked the block. The carb was in good shape though. Make an offer if you want it. -Mike
  4. lawnmaniac883

    lawnmaniac883 LawnSite Silver Member
    Messages: 2,613

    New carb should do the trick. Had the same thing happen on my 17hp kawi, it would run fine at times then would all of a sudden run like crap. Took it to the dealer like 6 times they cleaned carb replaced abunch of stuff from coils to hoses then I got so pist from the downtime that I went to my other dealer, ordered a new carb which at 150$ was no bargain but put the new carb on and it ran like new, has ever since.
  5. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Messages: 11,087

    Surging... hunting... reving up/dieing out???

    This symptom is MOST OFTEN caused by water/condesation in the fuel system.

    My advice is to go buy a fuel filter... and get a bottle of Sta-Bil.

    Turn your fuel off... let the engine die from running out the fuel in the lines.
    Change the filter and put the Sta-Bil in the tanks.
    Put your foot on the rear tire and rock the mower best you can to shake things up.

    Fire the mower back up and be patient.
    Let it run a while and see if it clears up.

    If it's still surging... try to do what you can with the throttle to make it happy and get it to run a while.
    Then try maxing the throttle out again.

    Also, it would be helpful to know if your unit has a separate choke lever or not?
  6. statman

    statman LawnSite Senior Member
    Messages: 268

    Thanks for the tip, separate choke lever.
  7. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    There are kits available for this carb, Your dealer is lacking the knowledge to properly look one up. I would try cleaning and installing a kit before buying a new one.

    With no numbers posted;

    (Keihin) Kit # 24 757 03-S

    (Nikki) kit # 24 757 18-S

    Spray all ports/passages and jets out with carb & choke spray cleaner with the little straw then follow with compressed air if available. Check fuel tank/s for water/trash, Flush fuel lines and replace filter.
    Check/replace plugs if needed since it's been running rich (probably fouled).
  8. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Messages: 11,087

    Hope the tip worked... cheap fix if that's all it is...

    I asked about the choke setup because sometimes the "associated" type where you push the one lever farther forward to choke it will get out of adjustment over time and cause problems.
  9. statman

    statman LawnSite Senior Member
    Messages: 268

    Tried filter, stabil,and carb kit with no luck. I'll be ordering a new carb Friday am

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