Kohler cv15s motor runs rich

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  #1  
Old 01-19-10, 02:39 PM
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Kohler cv15s motor runs rich

Hi all,
this is my first thread here so I hope I get it right.

Kohler cv15s 41508
I have a friends riding mower that runs rich any time it is put on a load or when the throttle is advanced to quickly.
The motor is installed on a mower which originally had a Briggs engine using gravity fed fuel system unlike the kohler set up with a fuel pump. The fuel pump is hooked up and working and the carb is clean. The motor runs great as long as the throttle is advanced slowly and the governor is not disturbed either manually or with a load.
Everything else works great except for this. I have worked on many mowers and understand how things are supposed to be but know I always can learn more.
From what I read the valves are not adjustable as they are hydraulic thinking maybe there was a problem there, but valves should not cause the mixture to become rich.
Any ideas??? this has almost got me stumped well I guess enough to ask for help
 
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  #2  
Old 01-19-10, 03:38 PM
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The idle mixture screw should be at 1-1/2 turns out from lightly seated. Have you checkd the solenoid on the bottom of the carb to make sure it is working properly?
 
  #3  
Old 01-19-10, 05:47 PM
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I assume you tried it without the air filter to eliminate the possibility of it choking the engine? If so, I would say there is a carb issue. Does this carb have the jet in the end of the fuel shutoff solenoid, or does it just have a rubber stopper on the end of it?
 
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Old 01-19-10, 06:30 PM
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Take a look at the choke butterfly and make sure it's open all the way when the choke is disengaged. Sometimes the choke linkage can hold the choke partially closed, and when a load is applied or the engine is accelerated, the choke can be sucked closed.

Just a thought....
 
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Old 01-20-10, 02:41 AM
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Hi all thanks for the replies
sorry should have mentioned that this motor has the Nikki carb with no adjustments except for idle.
Yes the fuel solenoid is working as should and it has the removable jet in the bottom of it, I even tried to make it smaller out of desperation with no change.
The air filter is trashed and was not using it.
The only thing that is different is the fuel tank sits above the level of motor in a gravity situation but I am still using the fuel pump, I can't imagine the fuel pump pumping more because of this and the carb never overloads. But it is all I got left to change, except for installing a kit. I was thinking that maybe the jet was too big but I am not convinced seeing as it will run fine at all speeds until a load is applied then it gets rich (bop, bop, bop, and so on) hope the sound effects help. The garage gets way rich smell of gas, the plug turns black. But when I put it back to idle and then slowly increase it will run fine.
 
  #6  
Old 01-21-10, 12:58 AM
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Are you sure this engine didn't do that on the other piece of equipment it was bolted to? Does the jet show signs of scratches around the hole like it has been drilled or tampered with? Sounds like the wrong jet or a flooding carb. It doesn't drip gas when it's turned off?
 
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Old 01-21-10, 02:28 AM
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Originally Posted by cheese View Post
Are you sure this engine didn't do that on the other piece of equipment it was bolted to? Does the jet show signs of scratches around the hole like it has been drilled or tampered with? Sounds like the wrong jet or a flooding carb. It doesn't drip gas when it's turned off?
Good Question!!
the jet does not show any signs of tampering, when I was asked to fix the carb was really gummed and I fixed that with carb clean and air. I was thinking also that the jet must be wrong for whatever reason. It is just that the kit runs about 30 dollars and I want to be sure. I read somewhere on the net that the kits only fix half the time, cause these carbs are not that good I guess. Really could use some mixture screws. No dripping after off. It will run at any speed good until I disturb it.
I think I will get a kit for it, it just seems like the most logical next step. And in the process will double check float height and so on which all looked good anyhow.
thanks, will post back if I get a solution but if anybody thinks of something else I am listening.
 
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Old 01-21-10, 06:34 AM
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I just went to Kohler and looked up your engine. According to the parts manual, your engine should have a Walbro #12 053 83 carb.
 
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Old 01-21-10, 01:13 PM
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Yeah, the nikki thing struck me wrong too. I don't recall kohler cv15 engines coming with nikki carbs ever. Maybe I'm wrong, but all kohler single cylinder command engines that I recall had walbro carbs on them. I think someone may have adapted a carb off of a briggs onto it or something similar. I haven't looked up the numbers, but that's my guess.
 
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Old 01-21-10, 01:48 PM
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Originally Posted by indypower1 View Post
I just went to Kohler and looked up your engine. According to the parts manual, your engine should have a Walbro #12 053 83 carb.
I just found all the numbers I had written down

Kohler Command SKH426U1G2RB CV15s
Nikki Carb 1205368
C128051
I just went to OPEengines.com parts lookup which directed me to Kohlerplus.com where you can download a service manual for this engine, and under fuel system it shows both the walbro and the nikki carbs, wish I had the walbro.
the carb looks like a stock install, fits perfect and all the linkage is straight forward.
I am thinking about making a jet as I work in a extrusion tool and die shop. I will make it small and see what happens.
 
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Old 01-21-10, 03:51 PM
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Hmm... I guess they did use nikkis. I suppose the only times I happened to take note and remember, they happened to be walbros. I think the smaller jet is about the only thing that makes sense at the moment.
 
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Old 01-22-10, 02:57 AM
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Originally Posted by cheese View Post
I assume you tried it without the air filter to eliminate the possibility of it choking the engine? If so, I would say there is a carb issue. Does this carb have the jet in the end of the fuel shutoff solenoid, or does it just have a rubber stopper on the end of it?
I remember seeing a rubber stopper and I never knew where it came from now that I think about it. The piece of rubber was about 1/2 inch long maybe a little shorter and it was thinner on one end. It was just laying there and I do not remember removing it from anywhere, actually was not even sure it came from the carb. Will look into this possibility further. Where would it go? There is a brass jet in the bottom of solenoid.
 
  #13  
Old 02-27-10, 05:54 AM
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I found my thread

the rubber plug where does it go in the carb?
 
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Old 04-26-13, 07:45 PM
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Did anyone find an answer to the Nikki carpuretor running rich?

I have a Kohler CV15S engine with a Nikki carburetor. It has the same problem as stated in this thread. It runs rich, with sooty exhaust, misfiring etc. but only when I move the throttle up quickly. If I start out low idle and move it up slowly to fast it runs OK. If I quickly move the throttle to fast it starts misfiring and smokes unless I pull it back to low idle.
It seems like it is flooding. The chuck plate is normal.
I keep wondering if I an orifice or jet is missing but there none in the rebuild kits.
 
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Old 04-26-13, 07:58 PM
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The rubber plug mentioned in previous posts goes into the tube that extends down into the bowl... the smaller tube on the side of the large tube containing the main jet.

If you take your bowl off and see this, make sure it is in place. Is the air filter new?
 
  #16  
Old 04-27-13, 03:25 PM
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Thanks Cheese, guess I should have updated, thought I did, but yes I had figured it out one day. Just studied the circuits and it made sense to plug that tube with something cause it was drawing fuel right past the main jet. The mower has been running fine for a long while now. Really appreciate all the help. Hope this helps someone else someday.
 
  #17  
Old 04-27-13, 07:24 PM
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Good, thanks for the update. Maybe that is the same thing that's wrong with the mower belonging to the person who resurrected this thread (Greenbank).
 
  #18  
Old 04-30-13, 06:58 PM
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Thank you very much for your reply.
Unfortunately, My carb has the rubber plug installed but still has the flooding problem, i.e. when the throttle is pushed forward from slow to fast some what quickly. If you move the throttle forward slowly it will reach high speed OK but then flood out under a load.
I think it is just getting too much fuel but I don't know why. The float and stopper are new and there is no adjustment for the float. The only adjustment on this carb is the low speed ideal.
I got a rebuild kit and installed it. I also replaced the auto shutoff solenoid.

Do you know if there is supposed to be an orifice or jet in the draw tube between the bowl and airstream?
I don't see one in the diagrams but it's hard to find the exact diagram for this carb. Nikki 1205368.
I do appreciate any ideas. Thanks
 
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Old 04-30-13, 08:34 PM
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Check you oil... is it thin and does it smell a bit like gas?
 
  #20  
Old 05-07-13, 02:58 PM
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Yes, the oil is thin and smells a bit like gas.
However, I found the problem. I had replaced the auto shut-off solenoid earlier. (I was fighting a not enough gas problem). It turns out the old solenoid had a orifice on it. I placed it on the new solenoid and it now runs great.
It was definitely getting to much gas.
Thanks for all your help. It was appreciated!
 
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Old 05-07-13, 09:28 PM
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Ok, but if there is gas in your oil, there is still a problem and you risk ruining your engine running it that way.
 
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