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Engine Tweaking

Discussion in 'Lawn Mowing' started by GillamLawn, Jan 29, 2005.

  1. GillamLawn

    GillamLawn LawnSite Member
    Messages: 13

    How do you tweak the engine to make it run at a higher RPM, I have a koholor command pro,
  2. lawncare4u

    lawncare4u LawnSite Senior Member
    from S>C>
    Messages: 399

  3. stumper1620

    stumper1620 LawnSite Bronze Member
    Messages: 1,889

    I recommend never messing with factory settings. Unless your engine is worn out and don't have the power to handle the job anymore and your just trying to get thru a season, otherwise you are just going to lead that motor to an early end. to tweak your rpms you need to adjust your govenor settings. if it is a newer motor you will probly have to bend or shorten the govenor rod.
    they all have their own way of doing it some have a screw, some you move the rod & spring to a different hole connecting to the gov. and some just are not ment to be. better off not to do it. :D
  4. edward hedrick

    edward hedrick LawnSite Senior Member
    Messages: 871

    I have a 22 Koh on my Scag. I added a enginaire pre cleaner

    and a larger Koh muffler. Seems to have a few more ponies. Ed
  5. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    Kohler V-twins do not react well to RPM with the blade engaged of over 3600. If it starts using more oil than usual back the RPM back off. This is usually a sign that it is working towards blowing a head gasket.

    Do not adjust the governor or the spring to adjust the RPM. If you can operate the throttle lever or have a helper operate it for you look at the cable where it attaches to the engine while moving the throttle. Move it to full wide open. You will see a small bolt that keeps the throttle from going any further. You need to back this bolt out until you get your desired WOT (wide open throttle). If you cannot get your desired RPM you will need to adjust the cable a little. Just loosen the screw that is holding the clamp down that holds the cable in place. Pull the cable out a little (1/4 inch) and see if you have desired RPM.

    If the engine starts surging with the blades on then you will have to adjust the governor spring. Let us know if you need to and we will tell you how to do it.
  6. jeffex

    jeffex LawnSite Bronze Member
    Messages: 1,933

    Here you may need this if you do what I did http://www.kohlerengines.com/service_manuals.html
    I tried to up my rpms by loosening the Governor and moving it forward . DON'T make that mistake. the service Manuel will tell you how to adjust the throttle cable but I would recommend LEAVING WELL ENOUGH ALONE. This need for speed cost me some money. I was using a small bungee cord to rev the motor and should have stopped there. I finally had to take it to a mechanic after several tries to get it back to "normal" and it turned out the Governor gear inside the motor fell out of place when I loosened the bracket off the pin on the outside of the crank case. I'm going to buy an 18 hp kohler and call it a lesson learned.
  7. stumper1620

    stumper1620 LawnSite Bronze Member
    Messages: 1,889

    Listen to the man that KNOWS his Kohler's!
    I thought the throttle side of the gov. had a non adjustable dead stop on it.
    did they change this on the newer twins?
    I personally still prefer to leave well enough alone unless its a dying engine.

    good post Richard.
  8. Oldtimer

    Oldtimer LawnSite Bronze Member
    Messages: 1,459

    If you have to ask how to speed up an engine you shouldn't be messing with it anyhow but everyone can learn from their own experiences so take a chance.

    Don't mess with the governor. You need a tachometer to set the rpm's and you might just find that you currently have a slow engine. If you really want more rpm's on single cylinder engines just loosen the plate that holds the throttle and choke cables and move it until you get the desired rpm's.

    I don't know what you can get on the single cylinder engines but twins will run just fine in the 4000-5000 rpm range. They just won't run for a long time turned that high but, what the heck, there are a lot of places to buy another engine.

    All the components on a piece of equipment are matched to a governed engine speed which is usually 3600 or 3750 rpms and there is nothing to be gained by running the engine any faster.

    On hydrostatic equipment there is always one thing that can be gained by turning up the rpms. That thing is hydro temperature and with bigger heavier mowers this can definitely shorten the life of the pumps and motors. This is especially a problem with systems using hydraulic oil or motor oil.

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