Kohler Carb Problems

Discussion in 'Mechanic and Repair' started by DQL10, Jul 15, 2012.

  1. DQL10

    DQL10 LawnSite Senior Member
    Posts: 292

    I just recently replaced my exmark's 18 hp kohler with a 25 hp kohler. I cant seem to get the engine to run with the 25 hp's carb but when I put the 18 hp carb on it runs but seems to run hot. My question is, am I just paranoid that its running hot or can I run the carb from the 18 hp on the 25 hp?

    Thanks in advanced guys!

    -Nate
     
  2. DQL10

    DQL10 LawnSite Senior Member
    Posts: 292

    The carb from the 25hp keeps flooding out the engine now. Any thoughts????
     
  3. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Nate, As the sticky above (Read This Before Posting) states, Post both the model and spec numbers off the engine.
     
  4. DQL10

    DQL10 LawnSite Senior Member
    Posts: 292

    I wish I knew the correct model and spec number. The only number my exmark dealer and exmark themselves could come up with is CH 730. Owners manual says model number is CH 25s but that number doesnt exist on Kohler's website.
     
  5. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Without a spec number I can't tell which carb you have, If it's a Keihin carb, rebuild kit is 24 757 03-S and fits 581 engines so your's should be in there.

    Get a kit then clean it good and put it in, I can't answer running the 18 carb. It could have a slightly smaller main jet and cause a lean/hotter than normal running temp, With EPA Kohler no longer sells individual parts to verify the jet....
     
  6. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

    The 18 hp carb is not a good replacement for the 25...
    The main jet in the carb is 2 sizes too small and it has a built in throttle stop that will not allow the butterfly to fully open...
    If the carbs were the same mfr and style...you could take the mainjet and throttleshaft off the 25 carb and install them on the 18 carb...
    Don't forget to adjust the governor...
    Posted via Mobile Device
     
  7. DQL10

    DQL10 LawnSite Senior Member
    Posts: 292

    I know they are both keihin carb's. As for the 25hp carb it does have an accelerated fuel pump and the one from the 18hp doesnt. It does run a bit leaner with the smaller carb. Might just have to buy a new replacement 25hp carb.
     
  8. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

    Try this...take the float and fuel needle out of the 18 carb and install them in the 25...they should be the same...
    Posted via Mobile Device
     
  9. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Ditto Slapper, Same kit is listed for the 18.....
     
  10. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

    Be careful not to bend the float...it is one of the most sensative floats I have ever worked with...you really need to use the manual to get it right...
    If it is a smidge high...it will flood...run rich...a smidge low...lean misfire..
    Basically it is adjusted at 22mm off seat....it takes a ruler and a pressure gauge to adjust it as the needle is spring loaded....
    My advice...treat it with respect...
    Posted via Mobile Device
     

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