Kawasaki 21 twin loses power when hot

Discussion in 'Mechanic and Repair' started by brucec32, Jul 4, 2003.

  1. brucec32

    brucec32 LawnSite Platinum Member
    Messages: 4,403

    I have a kawasaki 21hp twin cylinder engine that is having problems now at less than 100 hours. It runs ok, but feels a little weak initially, then loses more power after about an hour of use, until it eventually starts dying completely when you put any load on it at all. It will immediately restart, but is very weak. Dealer has replaced carb assembly but it still has the same problem.

    Any ideas I could pass on to help my dealer solve the problem?

    Searching the web, I came up with things like carbon buildup on the coil (resistance increases as it gets hotter) or valves not closing completely as the valve stem elongates slighty as it heats up and expands.

    Anyone else out there have a similar problem they were able to solve?
  2. Doc Pete

    Doc Pete LawnSite Gold Member
    Messages: 3,469

    Are you absolutely sure you're not running on one cylinder when it gets hot???? I had two coils go on my motor..... Take a wire off one plug while it's running, if nothing changes, that's the bad coil, if it stops, it's the other coil.
  3. brucec32

    brucec32 LawnSite Platinum Member
    Messages: 4,403

    Actually, after reading some posts here, it reminded me that it DOES sound just like one cylinder running when it's hot. Unfortunately, my dealer has the mower now for the 2nd time. I wish I'd thought to test that out before I gave it back to them.

    I'd be a little surprised though if they couldn't figure something so straightforward out by now. It's been about a month now.
  4. jrc lawncare

    jrc lawncare LawnSite Senior Member
    Messages: 420

    Like Pete says , could be a bad coil.Possibly a sparkplug going bad could be another option.Good luck.:(

    ADLAWNCUTTERS LawnSite Member
    Messages: 191

    just had the same problem with my 23 hp .it was one bad coil.i would unplug the sparkplug wire and use a good insulated screwdriver and check for a good spark.also run the mower for 10 min the pull the plugs the side with the bad coil plug will be cool to the touch. the other side will be hot.hope this helps
  6. brucec32

    brucec32 LawnSite Platinum Member
    Messages: 4,403

    Thanks Guys. The dealer shop manager called today and said it was ready. He said he would let me know in detail what they had to do to it but he gave his number and his cell phone cut out so I will have to talk to him later.
  7. brucec32

    brucec32 LawnSite Platinum Member
    Messages: 4,403

    Well, unfortunately, after getting it back and putting enough time on it to get it hot again........same thing is happening. It putters out when hot. With no load it runs fine. It will start right back up after dying while mowing. I checked, both cylinders ARE running, just really weak when hot. And it misses from time to time even when cool, and never seemed to have full power. I had a 18hp hp before and it seemed just as strong as this one with 21hp and much more torque.

    The dealer replaced the coils and plugs this time, and the whole carb assembly the first time.. Still doesn't work. What do you guys suggest? This is a 4 month old mower.

    Do I have a "parts changer" at work on it instead of a skilled mechanic? Or are they just impossible to diagnose?
  8. Doc Pete

    Doc Pete LawnSite Gold Member
    Messages: 3,469

    Bruce, it's a no brainer.... At 4 month's old, you want a new motor, end of story. They should be Lucky you ain't charging for lost time....
  9. redbull

    redbull LawnSite Member
    Messages: 182

    A new motor??? You can contact KW on-line, there maybe a service bulletin out on this unit. KW is very good at taking care of its customers
  10. brucec32

    brucec32 LawnSite Platinum Member
    Messages: 4,403

    Thanks, but my Exmark dealer GM and shop manager have been in contact with Kawasaki already. It seems to be a tough fix.

    They are now involving the Exmark maintenance rep and trying to contact Kawasaki about a new engine.

    Funny thing is, right before this happened, my TORO mechanic mentioned that he was having trouble getting Kawasaki parts in a timely manner (my mowers there were Kohler and Briggs powered) and that he would never own a Kawasaki bcause of it. He had to get a friend of his who was well-placed there to intervene on his behalf to get a new engine for a customer with bad new engine. The engine arrived the next day.

    I have two Kawis now. I have to say, i'm not that impressed so far. My 9 year old Kohler 12.5 felt stronger to me than the 12.5 on a new Exmark wb. Perhaps they're overrated.

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