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Hot!Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120

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spaceman
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2020/05/16 18:44:15 (permalink)
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Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120

Its 1 Kohler CH20OS 624CC   spec 64555, serial 2726715917. Toro Groundmaster 120
The throttle is pushed up to full throttle but it doesn't seem to be as high as it was. If I push on the
Govenor arm it revs up. There seems to some adjustment that is out of wack. I replaced the spring going to that
arm in the picture.   I have a new fuel pump and filter and spark plugs. It seems to startup fine and run fine but
just not able to get more RPMs in the full throttle position??????
 
When I kick the blades in they don't come up to full speed like they use to a few weeks ago. Something is acting
strange here. If I push on the Gov arm where that spring is in the picture the rpms come way up like they use to.
 
What do you think is wrong here????????????????  Hope someone can help.
post edited by spaceman - 2020/05/17 12:23:59

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    Roy
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/16 19:09:53 (permalink)
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    With the trottle up as far as it will go the lever attached to the other end of the cable should be against the stop. If not loosen the clamp and pull the cable then tighten the clamp.
    spaceman
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/17 13:06:11 (permalink)
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    I checked the cable in full throttle position and tightened it. Im adjusting this screw and locknut in the third picture and it seems to be making a difference.
    I wonder is there adjustments that can be made to the carburetor is there a carburetor on this engine twin Vee that can be adjusted. It might have been awhile since its been adjusted?????
     
    I found a service manual online and that screw with locknut is the highspeed adjustment screw looks like from
    what I read.
     
    post edited by spaceman - 2020/05/17 16:10:44
    Roy
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/17 15:31:51 (permalink)
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    If the engine is running smoothly there should be no reason to mess with the mixture screws.
    spaceman
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/17 16:12:19 (permalink)
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    Yes run good. The high speed adjustment screw might need adjusting. I found that in the service manual online.
    https://www.manualslib.com/manual/700336/Kohler-Ch18-745.html?page=44#manual
     
    I turned it some and it seems to be helping. Will play with it later today.
     
     
    spaceman
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/17 18:41:31 (permalink)
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    Well I adjusted everything but when I kick in the blades the engine doesn't seem to have enough power
    to run them up to speed they use to run at. The turn but not at the high speed they should run at.
    What could be causing this???????????????????
    Has me puzzled.
    Im not sure whats going on.
    Roy
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/17 18:45:40 (permalink)
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    Ground the spark to each cylinder. I supect one is dead.
    spaceman
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/17 19:12:01 (permalink)
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    What do you mean ground spark to each cylinder. What can be dead.. How do I do that?
     
    I have worked and replaced many things on this mower but this is a new one for me.
     
     
    Thanks for your help,, this is something new for me on this mower I haven't run into before. Im a newbie
    post edited by spaceman - 2020/05/17 19:41:28
    Roy
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/17 20:31:17 (permalink)
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    Remove the spark plug wire to one cylinder at a time then stick a screwdriver into the terminal and lay the shank against a metal surface. If nothing changes that cylinder is not producing power. If the engine quits the other cylinder is not working.
    spaceman
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/17 21:32:41 (permalink)
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    Ok will do the spark plug thing tomorrow and see what I find.  Thankyou very much for this help.
     
    Jack
    spaceman
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/18 12:22:08 (permalink)
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    I haven't tried the screwdriver into the spark plug terminal yet. I just wonder why do that and not just pull
    the sparkplug wire while engine is running and see if engine quits if Im looking maybe for a bad Ignition Coil on one of the cylinders.
    Im sure there is a reason for the screwdriver placed against some metal while the engine is running.
     
    Just wonder about that.
     
    post edited by spaceman - 2020/05/18 12:41:57
    Roy
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/18 12:47:10 (permalink)
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    You will figure that out when you pick yourself off the floor and catch your breath. The screwdriver next to some metal will tell you if the ignition on that side is working.
    AVB
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/18 12:53:36 (permalink)
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    But it is a good feeling to to get hit 12-15Kv. Getting hit 35Kv is even a better feeling.
    spaceman
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/18 17:26:48 (permalink)
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    Ok understand. Oh I forgot I had this spark plug tester in the tool box. I will try it first.
    If its a coil its not going to be fun getting to the flywheel, its behind part of the Frame on this Groundmaster 120. I might have to take some of the side frame apart just to get to it.
    Will check the front spark plug first since its easy to get to. The back one I have pull the gas tank up a little and
    take a rubber cover off over a access hole to get to the spark plug. There is a metal wall there..
    I installed new plugs just a few days ago when I thought they might be the problem but didn't think about the
    ignition coil. I bet that is what it is. Will find out tomorrow.
     
    Thanks guys for the help.
     
    post edited by spaceman - 2020/05/18 21:46:31
    spaceman
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/21 19:04:17 (permalink)
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    Well don't seem to have power to the front plug.  If I unplug the front plug the mower will still run.
    If I unplug the back plug and plug in the front plug it will not run.  I guess the front plug is not getting
    in power.  The ignition coil for it must be bad.  
    The question is how do I get to the coil under the cowling on the Toro GroundMaster 120. Has anyone replaced
    a coil on one of these. There is not much room between the side and the cowling to pull out.
     
     
    post edited by spaceman - 2020/05/21 19:07:46

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    Roy
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/21 20:48:16 (permalink)
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    Try changing the plugs first, use new ones.
    Roy
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/21 20:51:04 (permalink)
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    You may have to remove the engine to access the coils.
    spaceman
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/21 21:59:29 (permalink)
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    I replaced the plugs with new ones and just to double check this front one I just changed it with another new
    one and the same thing.  So looks like the coil for the front plug has gone out.
    My problem is how to get to the coil, to replace it. Yikes
    I wish I knew someone that has replaced one before and how they did it.
     
     
     
    post edited by spaceman - 2020/05/21 23:05:02
    AVB
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/22 07:52:14 (permalink)
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    As Roy hinted at you may need remove the engine just to get to the coils. I got a few riders here like the old shaft drive Cub Cadets where the engine has to partially come out to get to coils. Glad they don't fail very often but one of the reason the 2T engine crane here though I need a gantry type instead, my back just won't let me do this heavy lifting anymore.
     
    Yes 2T is overkill but I need it for auto engines and lifting of ZTRs when pulling transaxles assemblies. The Z925A is especially a pain as both has to come as one assembly.
    spaceman
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    Re: Engine won't rev up as high on full throttle Kohler CH20OS Toro Groundmaster 120 2020/05/22 12:04:01 (permalink)
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    I use to own a 2T engine lift and used it on my tractor when I split it to install a new clutch. I don't have it anymore.
    I do have a heavy duty Gorrila ladder I can adjust to different heights and it could straddle over
    the top of the engine and I could use a Come along hanging from 4 x4 post lying across two of the steps at the right height for the come along to hang from. I think would work.
    There two lifting brackets on the top of the motor to lift it.
    Might take a picture of the ladder and come along and the 4x4 post across two of the steps.
    post edited by spaceman - 2020/05/22 13:30:58
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