carb advice

Discussion in 'Mechanic and Repair' started by niceguy, Aug 15, 2011.

  1. niceguy

    niceguy LawnSite Member
    Messages: 29

    I have a kawasaki FH721 thats not running right. It would miss, surge, sputter and backfire occasionally. I removed the carb and sprayed cleaner and compressed air throughout and reinstalled and made no difference. I then did plugs, filters, oil, valves, checked coils and such in the process of elimination.

    I then removed and swapped carbs with an identical machine and have determined that the problem is indeed with that carb.

    My questions are...
    1. Is a rebuild kit available and are they reliable?
    2. Are they easy enough for one that is mechanically inclined( Id hate to have a hundred parts in a puzzle)
    3. What would I expect to pay for a kit vs. just replacing with a new carb.

    Gravely PM252Z's
    Model# 992066 25HP Kawasaki 52" deck w/ Eye Q
    Serials 000522 and 000523

    Thanks guys!
  2. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Messages: 2,247


    Yeah, I'd say you've isolated your problem to the carb. Following is a link to a typical fh721v carb. You didn't provide a complete engine number(found on a white tab or the side of the engine block(oil filter side as I recall). You can go to and select the proper engine and spec number to go to a breakdown of your carb.


    As far as carb kits go, Kaw doesn't provide one that I know of. About the only item that need to be changed out is the inlet needle, if it won't hold pressure. Floats rarely go bad.

    I would say you've still got some trash in one or more of your jets. Disassemble and keep track of where each part goes. Small plugs must be removed to access main jets. Clean all ports and reassemble in the proper places and you should be good to go.

    Check for any unusual wear in the throttle shaft as they sometimes will get sufficient wear to allow an air leak which will contribute to "hunting" for fuel.

    The real technicians may soon appear to "clean up" anything that I missed.
  3. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,002

    One thing to remember is the jet/s from the left and right carb bores are usually a different size. Don't get em mixed up.
  4. niceguy

    niceguy LawnSite Member
    Messages: 29

    Thanks guys, will give it a shot when i have some downtime. The white tag on the engine came unglued a few years back. I will check the block.
  5. topsites

    topsites LawnSite Fanatic
    Messages: 21,653

    To answer the question concerning carburetor kits, whether Kawasaki makes them or not,
    the below addresses the question in regards to any engine's carburetor:

    Kits are semi-reliable, sometimes they work, sometimes they don't, what makes them attractive is that they
    tend to sell for a lot less than the price of a carburetor meaning one might expect to pay $10-$15 or so for a
    kit vs. $50 to $80 for a carburetor, the drawback is that they don't always fix the problem.
  6. niceguy

    niceguy LawnSite Member
    Messages: 29

    Thats the answer on kits I was looking for. Kind of like, no real answer at all. Therefore, I will tear this little monster apart, clean, re-assemble and pray I did something good. If not, I will call my dealer to order a new one asap.

    Time to get started!
  7. weapons of grass destruction

    weapons of grass destruction LawnSite Member
    Messages: 228

    I would take out all the jets and gaskets and soak the whole carb in carb cleaner.
    Comes in 1 gallon paint can at your local autoparts store.
    works every time only time I ever needed a carb kit is on the tecumseh carbs.
  8. niceguy

    niceguy LawnSite Member
    Messages: 29

    What a day! I took apart the carb and laid everything out, valves, jets and all. When I removed the float from the bowl I found a piece of dirt right in the middle of the main jet about the size of a pinhead. Cleaned it all up and got it reassembled. Just as I begun to install it on the mower, I heard 2 of my kids screaming. They had climbed into the boat because they wanted to clean it out(hadnt been used in a few years) and stirred up a yellow jacket nest. They each got hit about 10 times before they jumped out and ran to the pool. My 5 yr old daughter had a mild reaction and being allergic to the e.r. we go. They both are doing well now
    Spent a few hours there and returned home to finished the install. Runs like a kitten!
    Thanks for the insight guys.

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