1. Missed the live Ask the Expert event?
    Catch up on the conversation about fertilization strategies for success with the experts at Koch Turf & Ornamental in the Fertilizer Application forum.

    Dismiss Notice

Exmark backfire question

Discussion in 'Mechanic and Repair' started by milfpig115, Apr 11, 2008.

  1. milfpig115

    milfpig115 LawnSite Member
    Messages: 2

    I purchased a used 52in Exmark Lazer last year with approximately 2000 hours on it. I believe its a 1996 model, I don't know the hp rating on the motor though it is a Kohler. The problem that I'm having is that its backfiring unless the choke is pulled half way out. With the choke half way out or when the motor is under full load (blades engaged moving forward , choke in) the motor does not backfire. I've changed the plugs and air filter but this seems more like a Lean condition to me. I was told by a mechanic at local landscape company that this could be caused by a leaking intake gasket. Does this seem like a cause or should I be looking at something else. Also what size motor is on this mower? Thanks.
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    It could be a intake gasket, Check by starting the engine cold then spray WD40 around the intake at the head area. If there is a leak the engine will pick up rpm. Myself, I have found more dirty/restricted carbs (main jet/passages) than intake gaskets.
  3. milfpig115

    milfpig115 LawnSite Member
    Messages: 2

    Thanks Restrorob I will give that a shot. Any idea what HP motor I have here?
  4. Winslow Mountain Lawncare

    Winslow Mountain Lawncare LawnSite Member
    from Lyme NH
    Messages: 36

    I had a 1999 52" HP with a 21hp kawi motor that did the same thing. I had the carb rebuilt and it still did it. I found if I shut it off with the throttle just over idle it didnt backfire......I am not sure why but it worked...

Share This Page