15 hp Kawasaki Trouble Shooting (Help!!!)

Discussion in 'Mechanic and Repair' started by Courtyard Services, May 29, 2007.

  1. Courtyard Services

    Courtyard Services LawnSite Member
    Messages: 2

    I have a 34Z Gravely with a 15 hp Kawasaki and this is whats happening. When we start it up when it is cold it runs fine. After it warms up it starts to miss on one cylinder. I changed the coil but it didn't seem to help. Has anyone ever encountered this. Your help would be greatly appreciated. Thanks
  2. MowerMedic77

    MowerMedic77 LawnSite Bronze Member
    Messages: 1,164

    Just a few questions I have to better help you.
    1. What is the model# and spec# for this engine?
    2. What spark plug are you running and what is the air gap set to?
    3. What color are the plugs when you pull them out?(black, oily, dry, etc)
    4. How many hours does the engine have and has it ever had valve adjustments?
    5. How are you testing for spark?
    6. What are you getting for a compression reading on both cylinders?
  3. procco

    procco LawnSite Member
    Messages: 4

    Sorry, don't mean to hijack this thread but I have a similar problem with a 20HP KAW (FD620D). Cylinder #2 keeps dropping out. I checked the resistance of both coils and everything is to spec (according to the service manual). Same goes for the pulser coils. I had a tech check the signals from the pulser coils with an oscilloscope and everything looks good. He checked the signal at the ignition coils and they look good there too.
    The engine was only running on cyl #1 and the plug in #2 was badly fouled. I replaced it with a new one and #2 was firing but when I hooked an inductive pickup timing light to the plug wire it seemed to be missing every once in a while. The same light on #1 never missed a beat. I'm completely stumped here.

    The engine has well over 300 hours on it and I don't know if the valve clearances were ever checked. Could this be causing the problem? Maybe incorrect valve adjustments are causing #2 to foul and that's why it's dropping out? After the engine warms up and runs for a while #2 cylinder drops out and I'm back to running on #1 only.

    Anything else I can try here? I figured I'd ask before I take the rad and everything out to check the valve clearances.

    Again, sorry to hijack the thread but I thought it made more sense to post here than start a new thread for a similar problem.
  4. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Sounds like you have the ignition pretty well checked out. It very well could be a valve acting up.
  5. procco

    procco LawnSite Member
    Messages: 4

    Hi Restorob,

    I checked the valve adjustment and everything looked good (#2 exhaust was 0.014 vs. 0.010 and that was corrected). After putting in a new plug in #2 and changing the oil (it was full of gas) the engine fired up and was running on both cylinders.

    I spoke with my dealer's service guy and he said there have been a lot of problems with gas puddling in the intake manifolds of v-twin engines (Briggs and Kohler had problems in the past) which caused plugs to foul. Many times this only affected one cylinder and maybe a swirl-spacer placed between the carb and intake would help correct this. He also suggested I use a hotter plug in #2 cyl and readjust the idle air/fuel mixture.

    He said there have been lots of complaints about the ignition coils being weak in these KAW engines. Do you have any experience with aftermarket or universal ignition coils in these engines? I'm thinking of swapping in two universal 12V motorcycle coils to see if they improve the way the engine runs.

  6. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    I only install OEM coils, Never tried aftermarket and don't even know if there is such a thing. If the resistance quality's are not the same on a motorcycle coil it could damage other components in the system, Be careful.
  7. procco

    procco LawnSite Member
    Messages: 4

    Hi Restorob,

    Just wanted to post a follow-up to let you know how things went.
    I purchased two generic 12V automotive coils (Echlin IC14 from NAPA) and installed them in place of the KAW coils (had to use a bracket to bolt them in place). The engine has never run better. EVER. It runs smooth at idle right up to full throttle and there is no miss or hesitation.

    The IC14 coils have a primary resistance of 3.25 ohms which is almost identical to the stock coils and there is no external resistor required. I also used 8mm plug wires to connect them to the spark plugs.
  8. mini14

    mini14 LawnSite Member
    Messages: 236

    would love it if pics were posted.thanks
  9. procco

    procco LawnSite Member
    Messages: 4

    Sorry for the delay. Here are a few pics of the NAPA coils installed.
    The OEM coils are still in place (but not connected).
    The two NAPA coils are mounted using the lower radiator bolts and connect to the original wiring using some extension cables we built.

    The engines (we have the coils installed on two of them) have never run better.





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