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Kohler K series carb rebuild for beginners

341 301 321 kohler k series

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#1 Mark 149 J. ONLINE  

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Posted February 23, 2018 - 03:00 AM

I'm sure someone has done a topic about rebuilding a kohler k series carb before but I thought I would anyways sense my Cub 169 need it's carb rebuilt.  I took lots of pictures to help out the first time carb rebuilders out there.  I hope this helps you out.

Edit:First, before you do anything check to see if the throttle shaft is worn out.  The shaft will move a lot from top to bottom but the side to side movement is key.  Simply move the shaft side to side and see how much movement there is.  It will move a small amount but if it can rattle around in the bore then it will need bushing installed or replace the carb.  The Kohler service manual has very detailed instruction on how to drill out and install bushings.   A worn out throttle shaft will make the engine run lean and make it very difficult for it to run smooth at idle.

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If all is good with the throttle shaft, I like to leave the choke and throttle shafts in the carb body.  It reduces the risk of having one of the small screws that hold the butterflies in from vibrating out while its running.  These tiny screws can cause damage to the engine if they get sucked into the combustion chamber.

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A lot, but not all, of the carbs on the Kohler engines were originally made by Carter.  Even the cheap Chinese knock-offs are copies of the Carter style carbs.  I try to use Kohler rebuild kits if possible.  The quality is better and the cost is just about the same price.  Here is the rebuild kit for the carb.  The carb to engine block gasket.  I buy these in a 10 pack in case I need one.  And the air cleaner housing to carb gasket.  I bought these off of Ebay.

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I took the carb off the engine.  Disassembled and soaked it in a gallon can of carb cleaning solution that I bought at the local parts stores. I also keep on hand cans of carb cleaning spray.

Here is what the carb looked like after it's been cleaned.  

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I use a rubber tipped air gun to clean out any dirty in the main body of the carb before I start assembling the carb. 

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I also make sure all of the passages are cleaned out with a very small gauge wire to dislodge any pieces of sand.  I find speak wire works really good. 

Edit:  On the end of the carb that bolts to the engine, you will find a very small opening in the bore of the carb.  This is part of the idle circuit. 

post-78623-0-54747100-1519490489_thumb.j post-78623-0-76344900-1519490511_thumb.j

This opening will get plugged with sand.  I like to take a small gauge multi-strand wire and insert it into the opening to make sure it not obstructed.

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Here you can see the idle screw and small opening are directly in line with each other.

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First up is installing the main jet.  These sometimes can be difficult to remove if they're corroded.  Make sure the holes on the side are open and clean.

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Install this into the main body.

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Make sure it is nice and tight and past this hole.

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Next, install the main fuel needle.  It has one hole at the bottom and several at the top which are connected.  This is were the speaker wire really helps along with air.

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Tighten it until it lightly seats.  You should be able to see it cleanly in the main jet that was just installed.

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Now we turn our attention to the float valve and gasket.  I use a ground down 3/8 socket to remove and install this valve.  It makes the job a lot easier and you won't break-off the attachment points for the float.  They sell a special tool for this as well.

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Install the needle valve and float with pin.

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Holding the carb upside down make sure the float sits parallel to the carb body or 11/64 of an inch according to the manual. 

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Mine was not so I bent this tab on the float until it did.

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Better!

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I also check for float drop.  

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Looks good!

I like to make sure the float valve is working correctly by putting the fuel inlet up to my mouth and blowing gently.  I manual move the float to make sure the valve needle drops and seals when I move the float with my hand.  Works good!

Now install the bowl o-ring.

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Then the baffle gasket.

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Add the new gasket to the bowl nut.

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Carefully place the bowl onto the carb body making sure the o-ring and baffle gasket stay in place and centered.

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Add the bowl nut.

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Install idle screw and tighten until it lightly bottoms outs.

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I then back the idle screw and main fuel needle out 1.5  to 2 turns each.  This should allow the engine to start.  With engine idling adjust the idel fuel needle until it runs smoothly.  Go to full throttle and adjust the main fuel needle.

 

You're Done!

I hope someone finds this helpful!  If anybody else has a suggestion or  what you do when rebuilding these carbs please share it by responding. 


Edited by Mark 149 J., February 24, 2018 - 03:20 PM.

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#2 karel OFFLINE  

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Posted February 23, 2018 - 03:47 AM

Excellent! I have a cub that need a go through. no high idle. purrs like a kitten though. I've bought Kohler parts through," I save tractors" Best prices you'll find.


Edited by karel, February 23, 2018 - 03:51 AM.

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#3 Gtractor OFFLINE  

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Posted February 23, 2018 - 04:15 AM

Excellent!!!  :thumbs:

 

This should be pinned and in a better location on the site.


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#4 EricFromPa OFFLINE  

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Posted February 23, 2018 - 05:01 AM

I found that setting the float parallel the engine will cough and sputter at times when mowing on uneven ground. Setting the float angled down a tad bit fixes that problem.

 

Also if you have problems with idling you can enlarge the small holes on the main needle near the point a bit with a barbed oxy acetylene torch tip cleaner. You will get much better response while adjusting the idle mixture screw and it will idle down much smoother.


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#5 Vrdaddy OFFLINE  

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Posted February 23, 2018 - 08:15 AM

thanks for sharing, lots of good info. here. i have a 12 horse Kohler that i bought one of those coppy off carbs. for, have'nt put it on yet, was trying to find a full rebuild kit for the carb. because like you said the main jet can get tight, well this one was "TIGHT" had to drill and use an easy out to extract it. ebay does'nt sell any of the major parts other than the type of kit you show here. Kohler seems to be the same way,where can you get mainjets and needle valves for these carbs.?


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#6 Mark 149 J. ONLINE  

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Posted February 23, 2018 - 10:34 AM

Excellent! I have a cub that need a go through. no high idle. purrs like a kitten though. I've bought Kohler parts through," I save tractors" Best prices you'll find.

Thanks for the kind words!  

I've used that supplier as well.  They also are available on ebay.

 

 

Excellent!!!  :thumbs:

 

This should be pinned and in a better location on the site.

Thanks!  I was a little surprised by all of the "thanks you" and kind words!  



#7 Mark 149 J. ONLINE  

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Posted February 23, 2018 - 10:38 AM

I found that setting the float parallel the engine will cough and sputter at times when mowing on uneven ground. Setting the float angled down a tad bit fixes that problem.

 

Also if you have problems with idling you can enlarge the small holes on the main needle near the point a bit with a barbed oxy acetylene torch tip cleaner. You will get much better response while adjusting the idle mixture screw and it will idle down much smoother.

Good information Eric!

I've haven't noticed the coughing and sputtering but my property is very flat and I don't mow with my tractors.

Good fix for the idling issue!

Thanks



#8 refracman OFFLINE  

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Posted February 23, 2018 - 10:53 AM

Also remember to check throttle shaft play. this can lead to hard starts, poor idle / throttle response.

There is a shaft replacement kit but I make a brass bushing out of a cheapo brass punch and install. it takes a little bit to install but its a lot cheaper that a shaft kit 


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#9 Mark 149 J. ONLINE  

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Posted February 23, 2018 - 11:29 AM

thanks for sharing, lots of good info. here. i have a 12 horse Kohler that i bought one of those coppy off carbs. for, have'nt put it on yet, was trying to find a full rebuild kit for the carb. because like you said the main jet can get tight, well this one was "TIGHT" had to drill and use an easy out to extract it. ebay does'nt sell any of the major parts other than the type of kit you show here. Kohler seems to be the same way,where can you get mainjets and needle valves for these carbs.?

Unfortunately I can't find even a part number for the main jet.  They still make the main needle valve but that doesn't help you.  Maybe somebody else will be able to help you with this one.


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#10 Mark 149 J. ONLINE  

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Posted February 23, 2018 - 11:33 AM

Also remember to check throttle shaft play. this can lead to hard starts, poor idle / throttle response.

There is a shaft replacement kit but I make a brass bushing out of a cheapo brass punch and install. it takes a little bit to install but its a lot cheaper that a shaft kit 

Good point!  If the throttle shaft is really worn it doesn't matter what you do to the carb the engine will not run right.



#11 chieffan ONLINE  

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Posted February 23, 2018 - 11:41 AM

Very good information though I don't own a Kohler.  One cub has a Briggs and the other is a Kubota.


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#12 EricFromPa OFFLINE  

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Posted February 23, 2018 - 02:35 PM

Brian Miller has them listed on his site for $10 + shipping. NLA through Kohler and I'm having problems even finding a part number.

 

Just past the Floats near the top of the page.

 

http://gardentractor...om/a1miller.htm

 

New Brass Main Jet/Nozzle (Emulsion Tube). Fits all Carter/Kohler #26, #28, #30 carburetors used on Kohler K-series and early Magnum engine models K241, K301, K321, K341, K361 and opposed (flathead) twin cylinder engines.

  • $10.00 each, plus shipping & handling

 

 

I have an old #26 in the shed somewhere. If I can find it that I might be able to get the nozzle out of it. The carb has a worn throttle shaft but the Nozzle should be ok is I can get it out in 1 piece.


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#13 Mark 149 J. ONLINE  

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Posted February 23, 2018 - 03:23 PM

Brian Miller has them listed on his site for $10 + shipping. NLA through Kohler and I'm having problems even finding a part number.

 

Just past the Floats near the top of the page.

 

http://gardentractor...om/a1miller.htm

 

New Brass Main Jet/Nozzle (Emulsion Tube). Fits all Carter/Kohler #26, #28, #30 carburetors used on Kohler K-series and early Magnum engine models K241, K301, K321, K341, K361 and opposed (flathead) twin cylinder engines.

  • $10.00 each, plus shipping & handling

 

 

I have an old #26 in the shed somewhere. If I can find it that I might be able to get the nozzle out of it. The carb has a worn throttle shaft but the Nozzle should be ok is I can get it out in 1 piece.

Thanks Eric!  I didn't think to check there.  That is still cheaper then a new carb but the main needle screw are about $15 to $20 as well. $30 to $40 total.


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#14 LilysDad ONLINE  

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Posted February 23, 2018 - 03:28 PM

Good information Eric!

I've haven't noticed the coughing and sputtering but my property is very flat and I don't mow with my tractors.

Good fix for the idling issue!

Thanks

According to Brian Miller, some needle valves have two holes at the point and they don't have an idle problem. Other ones only have one hole and he says to drill that one hole out with a #60 drill bit.

 

 


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#15 EricFromPa OFFLINE  

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Posted February 23, 2018 - 03:46 PM

PM sent.

 

 

IMG_20180223_151844.jpg IMG_20180223_151751.jpg

 

 

IMG_20180223_153823.jpg

 

 

This needle is a single hole needle that I enlarged the hole on. Tested in a #30 carb on a K321 and it idled very well.


Edited by EricFromPa, February 23, 2018 - 03:53 PM.

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