Kohler 41508 with Nikki carb

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  #1  
Old 02-25-10, 03:03 AM
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Kohler 41508 with Nikki carb

Hi,
If you remember from another post I have this kohler cv15s engine with a nikki carb that runs rich, I would like to either replace the main jet or put a whole kit in it, but cannot find a specific kit for the carb.
The one I do find is part number 12 757 03 5...I believe this is for the walbro carb and it does not come with main jet. The high altitude kit does, but again probably for the walbro. Are these kits the same for either carb???
And another question, is there something else on this engine that might cause the motor to run rich when given a slight load/change in throttle position? It will run fine if the throttle is feathered up or down but if you change it quick or put a load on it it will start running rich
I know I could/should just get another carb with adjustable main/idle jets but there goes the budget.
Any help please
 
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  #2  
Old 02-27-10, 04:33 AM
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I found this

http://www.smallenginesuppliers.com/...ervicekits.pdf

maybe I will find what I need
 
  #3  
Old 02-27-10, 05:34 AM
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Ok I found a rebuild kit but I do have a question

There was this rubber plug that i found and I did not know where it came from while breaking down this nikki carb.
My previous thread has seemed to disappear, anyhow I see this plug in the kit and since I do not know where it goes can someone help.
this rubber plug was mentioned in my other thread.
Maybe this could be my running problem!!!
The only schematics of carbs are the walbro's
any help?
 
  #4  
Old 02-27-10, 06:07 AM
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The rubber plug I couldn't say. I would get the numbers off the carb and look for a parts diagram on line if you don't get the answer here.

Your engine acts like it's running rich all the time, though. First check things like air filter and exhaust restrictions. Then if the kit doesn't take of it with the plug in place, you can lean up an engine by dropping the fuel level in the bowl = adjusting the float level or in an all position carb by resetting the metering lever.

Normally if you have go to either of these things as a fix you're compensating for another problem. The ignition could be weak or off, the compression may be low, or the valves may not be moving properly = cam or adjustment.
 
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Old 02-27-10, 07:53 AM
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I just looked for the rubber plug and of course cannot find it, had it but lost it.
Just fired this motor up after it has been outside for 2.5 months and the temp is 35 with 20 mile winds, and the battery was good and it fired up right away and ran good. then I tried adjusting the throttle quickly and immediately it went rich.
it runs as expected until a load is applied.
well I need to get a kit for it and really go through it
the choke is open when it does this also.
here is a pic of the kit that is on the bay right now



the rubber plug that is now missing is next to the brass plug and the spring
 
  #6  
Old 03-06-10, 07:50 AM
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I found it
bought a kit 12-757-27-s kohler kit for the Nikki carb which came with the rubber plug.

the rubber plug goes in the idle pickup hole that is next to the main pickup blocking off the idle pickup from the fuel bowl and makes the idle circuit draw from the main circuit. Once put back together it ran fine. I guess that when the main circuit opened up it would also draw fuel from the idle circuit which was without the plug in place bypassing the main jet, so it was getting fuel from both places causing it to run rich. I knew the rubber plug went somewhere but it was loose when I opened up the carb.
There is no documentation that I could find on the net which shows a breakdown or exploded view of this carb, only the walbro.
 
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Old 03-06-10, 10:30 AM
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Well the important thing is you got the little beast going. Seems like an odd setup, but maybe more are like that. I wonder why it fell out of its little hole in the first place.

Thanks for posting back. Some time or another someone else will be looking for information on the same thing. You've made their fix a little easier.
 
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Old 03-06-10, 02:12 PM
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yeah they could have just blocked off the area permanently, but I guess it is alot easier to clean out the way it is. I do not remember ever pulling the plug out of anywhere. It was just there on the bench. Been researching this for awhile now, I thought about making a diagram myself to share with the community, cause like you say someone else is sure to have this same problem.
just fired it up again and it runs great, no more richness. and it idles better too.
 
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Old 07-07-10, 07:56 AM
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Diagram

You would be doing the world a huge favor if you posted a diagram of the nikki carb. I'm a newbie to carbs and I've been trying to fix the Nikki on a Kohler cv15s. The only images I could find were of the Nikki twin carb and it's nothing like what I have. Since this is the first carb I've ever worked on, I'm really working blind here.

The good news is that the carb is clean as a whistle. The bad news is that I'm having to run the engine full choke in order keep it running and I'm not getting much power out of it. I assume that means it's not getting enough gas. I've changed the fuel line and installed a new filter but it didn't help.

My next move is to make sure the solenoid under the bowl is opening and to install the needle properly into the float. It fell out when I took the float off and not having a diagram, I just slipped it back into it's hole. I've since seen a photo which shows the bottom of the needle installed into the float itself, so I've got to go back and install it properly and hope that will makes things better.

Any suggestions you may have would be greatly appreciated.
 
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Old 07-07-10, 09:48 AM
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Correctly installing the needle is a likely bet. Fuel flow is probably shutting off before the bowl is to the correct level.
 
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Old 07-07-10, 12:08 PM
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I'll give it a try as soon as I have time and it's not 98 degrees outside. Ugh!
 
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Old 07-08-10, 02:16 PM
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Originally Posted by masterstroke View Post
You would be doing the world a huge favor if you posted a diagram of the nikki carb. I'm a newbie to carbs and I've been trying to fix the Nikki on a Kohler cv15s. The only images I could find were of the Nikki twin carb and it's nothing like what I have. Since this is the first carb I've ever worked on, I'm really working blind here.

The good news is that the carb is clean as a whistle. The bad news is that I'm having to run the engine full choke in order keep it running and I'm not getting much power out of it. I assume that means it's not getting enough gas. I've changed the fuel line and installed a new filter but it didn't help.

My next move is to make sure the solenoid under the bowl is opening and to install the needle properly into the float. It fell out when I took the float off and not having a diagram, I just slipped it back into it's hole. I've since seen a photo which shows the bottom of the needle installed into the float itself, so I've got to go back and install it properly and hope that will makes things better.

Any suggestions you may have would be greatly appreciated.
I have to figure out how to make a diagram, will try to work on this.
basically the rubber plug when looking at the carb from the bottom plugs the bottom of the idle circuit separating it from the fuel bowl. The idle circuit draws fuel from the main circuit, but if the rubber plug is not there then it would draw fuel from the bowl up thru the idle and main circuits when the throttle is opened causing the mixture to be very rich.
here is a homemade pic, sorry no detailed schematic
 

Last edited by 5dollaralien; 07-08-10 at 03:31 PM. Reason: added pic
  #13  
Old 07-09-10, 08:28 AM
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Thanks 5dollaralien. Every little bit helps.
 
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Old 07-11-10, 07:27 PM
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Arrrrgh! I've taken the carburetor and solenoid apart more times than I care to count and I've poked wires through every single hole where fuel should come in and everything's clean and open. I've changed the fuel lines and fllter, I've checked the fuel pump, there's plenty of gas getting into the carb bowl, but the thing still needs to be run with nearly full choke (yes, I've checked the choke and it's properly adjusted). I think I'm going to start my own thread and see if anyone out there has any ideas before I break down and buy a new carburetor.
 
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Old 04-27-13, 03:32 PM
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Late response, but have you checked your intake gaskets for a leak?
 
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