Kohler Command CH25 PS 68613

Discussion in 'Homeowner Assistance Forum' started by ScagTigress, Sep 30, 2018.

  1. ScagTigress

    ScagTigress LawnSite Member
    Messages: 8

    Hello All,

    I am looking for help with the above engine on my SCAG Turf Tiger. Of course, being a Kohler the silver tag on the engine has long since vacated the premises! I think that this is the right numbers according to the Owner"s Manual for the SCAG. Model: STT61A-25CH, SN 6712066.

    So long story short, ended up having the engine pretty much rebuilt, new pistons/rings, cylinder heads/gaskets, starter, and few minor misc. parts. It now runs beautifully wide open but cant really throttle it down and keep the blades running at high idle under load. It fired up great, tried to mow with it, thinking I could use my speed to slow things down with the blades turning and being under load. As I got to the way heavier grass it started to slow down, blades stopping, engine sounding like it was gonna fly right off the mower, and me freaking out, worrying about blowing up my pretty much brand new engine! Throttled it down as much as I could, shut it off, and tried staring it again. Took a couple tries to get it started, then it was the same, high idle, but not much speed. Worked my way back to park it in the shop until I could figure out what is going on.

    I don't have fancy meters, let alone know how to use them, but I'm learning more each time I dive into this. And let me be clear, I did not do the pistons/rings, head covers, or starter! I got to the part where the covers needed replacing because I was going to replace the gasket on the side with fuel pump, because I noticed oil leaking, and following my other sources(YouTube, manuals, co-workers etc.), seemed like a doable/manageable place to start. Got the first 3 bolts out without a hitch! The fourth proved to be a challenge as it became apparent that since it was cross threaded, and broke while trying to remove it, something else bigger had probably been going on with this thing. So after a few trips to the store for screw extractor, retractable magnet, and few other odds and ends, I reached the limit of what I was willing to damage further, and called upon a friend, much more skilled than I, to help with the rest.

    So, I apologize if this is too wordy, but I was also hoping to generate a giggle or two and my expense/experience in navigating my troubleshooting and attempted repairing!

    It seems that there may be a linkage that is missing or not placed correctly. The diagrams I have and tried to follow are good at showing the exploded views of the parts but not so much at where exactly they should all be attached at the various points such as the carburetor, the choke, and the governor.

    Sooo, slow me down, narrow down something specific to start on. The thought of carburetors makes me cringe, but I'm here to learn and try!!

    Thanks so much if you've made it this far:)
     
  2. Mow-Daddy.com

    Mow-Daddy.com LawnSite Fanatic
    Messages: 5,679

    One thing I've always done before ever taking something apart. In the olden days before smart phs. Draw a diagram of how thing's are attached. Label hoses, wires, cables with masking tape. Now I just snap pics with phone. Re-assembly then is not guess work.
    It does sound like your governor is not keeping up rpms.
    But as my other post on your other thread. You don't control forward speed with throttle. The throttle should be maxed out anytime your mowing.
     
  3. OP
    OP
    ScagTigress

    ScagTigress LawnSite Member
    Messages: 8

    Hi Mow-daddy, and Thank you,

    Yep, I do know that about controlling the speed with the sticks and having the throttle wide open while in use. I'm not very good yet at describing what exactly is happening. I'm wondering if the thing was not set right before i got it. When it was rebuilt it was put back together just like it was, according to pictures taken before disassembly, assuming it was correct. Before the rebuild it felt like it was never running wide open and the throttle lever on the control panel next to the seat never really went all the way forward to a full open position. But, mostly seemed to run OK and mow OK. I did notice that it was going through quite a bit of oil, and appeared to be leaking from the R side head cover somewhere. I also discovered that oil was getting to the base plate under the low profile air cleaner and carburetor. I noticed it was missing the breather seal under the Element cover and the O ring under the Air cleaner knob. That was the begging of the "series...."

    Give me a minute to get my photos up. I did take some photos..
     
    Mow-Daddy.com likes this.
  4. Mow-Daddy.com

    Mow-Daddy.com LawnSite Fanatic
    Messages: 5,679

    This is why I kept mentioning throttle needs to be w.o.t.
    Your post makes it sound like you were throttling down with blades engaged.
    It sure sounds like governor isn't keeping up with demand.
     
  5. OP
    OP
    ScagTigress

    ScagTigress LawnSite Member
    Messages: 8


    So here is what it looks like:

    IMG_4955 Controls.JPG IMG_4958 Controls 2.JPG IMG_4959 Controls 3.JPG
     
  6. OP
    OP
    ScagTigress

    ScagTigress LawnSite Member
    Messages: 8

    I'm thinking Governor too, tried adjusting by loosening the governor, pushing it all the way toward the carburetor and the turning the rod counterclockwise, then re-tightening. Didn't change anything.
     
  7. Mow-Daddy.com

    Mow-Daddy.com LawnSite Fanatic
    Messages: 5,679

    It's hard to tell from a pic. But the one cable looks like it is binding against the linkage. It looks like it is bowed even.
    On your 3rd pic. The bottom pic.
    The cable on the right side of clamp.
    I have all Kawasaki engines so I'm lacking on kohler.

    Hopefully someone with kohler experience will jump on thread.
     
  8. OP
    OP
    ScagTigress

    ScagTigress LawnSite Member
    Messages: 8

    Yep, we agree it like oks like that cable is bowing. When you move the lever though it operates ok, but seems it shouldn’t be that way & needs adjusting.

    Hoping someone with Kohler knowledge jumps in. I appreciate your replies though, thanks!
     
    Mow-Daddy.com likes this.

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