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25hp Kawasaki Problems. Need Help!

Discussion in 'Mechanic and Repair' started by jtkplc, Oct 16, 2009.

  1. jtkplc

    jtkplc LawnSite Silver Member
    Messages: 2,656

    I've got a 25hp Kaw. with 1400 hours on a Wright Stander and 2 weeks ago it started acting up. I'm pretty new to mechanics of small engines and I don't know what might be wrong.

    What's happening is the engine sputters. When the rpm's are raised from idle it sputters worse and then gets better slightly. When the engine is put under load, either a rapid acceleration to top speed from a dead stop or the engagement of the blades, the engine really sputters and bogs down. This problem is not there 100% of the time. Many times the mower will work perfectly. Other times it will be fine and then after a few minutes of operation it will start to sputter. Still other times it will just be sputtering right from start up.

    I've already replaced the fuel filter, checked the spark plugs and they are fine. This problem started after I checked the valve clearance but I rechecked them and they are tight and at spec. I also had a negative battery cable break at the same time as the valve check but it, too, was replaced.

    I'm also noticing a tiny bit of blue-ish smoke from time to time on either start up from cold or when the rpm's are raised. There isn't very much that comes out the exhaust, nor am I noticing my oil level dropping any. And again, I'm not seeing the smoke everytime I start the engine or everytime the rpm's get raised from idle. That, too, comes and goes.

    So, can anyone help me put this together and help me figure out where to look? I have a digital voice recorder that I can get a clip of the engine doing it's thing to help you hear the problem if that would be of any help.
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    There could be a few things causing this, Just because a plug looks good doesn't mean it is good. They are cheap and easy enough to replace to eliminate as the problem. If they don't help take them back out and put them in when you do need them.

    It's possible the carb is leaning out and in need of a tear down and cleaning, Try slowly applying the choke while it's sputtering. If it smooths out clean the carb.....

    The engine model AND spec numbers would be helpful should neither of the above make a difference in running.
  3. jtkplc

    jtkplc LawnSite Silver Member
    Messages: 2,656

    I forgot to say that I did replace the spark plugs and that didn't change anything. I will try the other thing you mentioned tomorrow while I'm doing maintenance and I'll report back. Thanks for the help so far.
  4. chesterlawn

    chesterlawn LawnSite Senior Member
    Messages: 704

    Also check the fuel lines for cracks. Mine did the same thing and the fuel line was bad between the filter and the carb.
  5. jtkplc

    jtkplc LawnSite Silver Member
    Messages: 2,656


    While doing maintenance today I checked the fuel lines and they looked good. I also put the choke on slowly while the engine was running bad. Once the choke was engaged around 50% the engine started to die. It did not improve the sputtering.

    Here is the engine information from the decal:
    Code: FH721V-CS33-R
    E/NO: FH721VB57666

    Let me know where else I should look. And thanks again guys for your help. This problem is really above and beyond my beginner expertise with mechanics and repairs. It's much appreciated!!!:waving:
  6. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Since this started after a valve adjustment, Did you make sure each piston was at TDC compression stroke with a small screwdriver inserted into the plug hole touching the piston ?
  7. jtkplc

    jtkplc LawnSite Silver Member
    Messages: 2,656

    The opposite valve was open when I made the adjustment. Would that make a difference?
  8. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Sure enough, Each piston must be rotated to TDC before the valves can be properly adjusted;

  9. haybaler

    haybaler LawnSite Senior Member
    from ma
    Messages: 511

    If you don't know what your doing, don't do it. you can cause severe engine damage by having your valves not adjusted properly. Have someone do it that knows what there doing. If you ever have the condition your describing (and you haven't messed with the motor) try draining the carb, very common to get water in there and make it run like crap. there is a little screw towards the bottom of the carb you just turn counter clockwise and the gas/water drains out, turn you fuel line off before you do this and then when gas stops coming out turn it back on and let it run for a second and then tighten screw back.
  10. jtkplc

    jtkplc LawnSite Silver Member
    Messages: 2,656

    Help me understand what the difference is between doing it at TDC when both valve are closed or doing it one at a time (the way I did it). Isn't closed, closed? Also, if this is the problem, why does it come and go. If a valve was out of adjustment, it should always be acting up...or not?

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