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Sams Shop Talk

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China made Kohler K series Carburetor modifications

SmilinSam

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Many in here have bought and used the China made replacement carburetors off Ebay for Kohler single cylinder K series engines . Most of us who use these for replacements on a regular basis have come to understand that quality control  where they are made is not the best.  The rule seems to be that about one out of three or four carbs you get is going to be no good for one reason or another. On the last bad one I had  the throttle shaft butterfly would bind up against the carb body throat. If you buy from a well established Ebay seller, they are aware that a certain percentage are no good. You contact your seller, tell the it does not work and why, and they just send you another. My experience anyhow thus far. No big deal, other than some waiting for another carb.

What is a big deal though, is that on all these China made K series carbs that I am aware of  is that the choke shaft control plates are all installed backwards. The plates should have the cable holes pointing towards the air cleaner. On the China made carbs, the cable holes are pointing towards the engine block. What this means is that if you can get the cable hooked up, "on will be off " and "off will be on" in relation to the tractor cable operation on the tractor. Here is the proper fix to this problem....

First you have to remove the shaft from the carb. To do this you need to remove the 2 butterfly screws. As far as I can see that factory does not use a thread locker to secure the screws, which helps in this operation. You need a phillips screwdriver that is  properly sized to fit the screw heads.. Too small and it will slip and ruin the screw head, too big and it wont bite well enough...and again ruin the screw head Use the correct screwdriver because you only have the one chance to get the screw out without creating more problems. While turning, and turning real slow, you have to put a good amount of pressure downward onto the screw head.  You have to be able to "feel" whether the give in the turning action is from the driver slipping or the screw breaking free.  Breaking free will result in a quick short "pop" feeling. If you damage the screw head, well , I don't have any advice on how to proceed from there.....so don't ruin the screw head.

Once the screws are out and the butterfly is removed, its time to slide the shaft out. Before doing this, set the carb flat  on a table with the engine block side down so you are looking down onto the choke shaft. reason for this is that on the left side of the carb were the shaft is supported, there is a tiny little detent ball and spring that will fall out. Even sitting like this the ball may roll out as you slide the shaft out. Be prepared to catch it. If it falls onto the floor, your chances of finding it are slim to none. This I know first hand to be true.....

Take the choke shaft and get yourself  a small punch that fits in the center half of the flared end of the shaft on the control plate side. 

medium.DSCN2766.JPG.74224e14102dd8cae7f4

 

 Stick the open end of the shaft into a vise  and close the vise down against the shaft, but not tight, so that the control plate is resting on the top of both jaws of the vise. (The above picture is after I have already repositioned the plate, but you will drop the assembly in the vise  like this and use a punch that is smaller than the outside diameter of the flared end of the shaft.)

Using the punch and a hammer, drive the shaft out of the control plate. This will let the flared part of the shaft be force straight up without losing any of the metal. That metal will have to be there to be peened back down once you reposition the control plate.

Your shaft should be like this now..

medium.DSCN2763.JPG.3f49caae9cb2588bf59e

You see the flat sides of the shaft clearly.  The flat sides of the plate are not so flat, but they are there. What you do now is just flip the plate over so it faces the other direction and fits on the shafts flat sides. There is a bent over thump lip on the shaft. It will have to be cut back so it does not hit the side of the carb. I don't cut them completely flush. I leave a little lip there. for stiffness in the plate.

medium.DSCN2767.JPG.281c1fbd772af715e28d

Once the plate is flipped, you can use a small ball pein hammer to peen the end of the shaft tightly over the plate. You will have to set the opposite end of the shaft on a anvil or other firm surface. Do not hit it super hard as you are going to flare he opposite end of the shaft as it is. Once the peening is done, you will likely have to file the edges of the open end of the shaft a little to remove any swells, this so the shaft will be able to slide through the carb body. Check and file , re-check and file as need. Wipe the shaft clean after each filing.

You will have to again lay the carb with the block side of the body down and the air filter side up. Make sure the little spring is in the hole it goes in on the laft side of the carb. Get a tiny flat blade screwdriver that is magnetized and get the little metal detent ball on the end of the screwdriver , then hold the ball in the hole against the spring while you slide the shaft back in. You should be able to get the shaft to go over the ball/spring as it goes through. Rotate he shaft to the proper position . Ball should snap into the detent slot in the shaft as the business end of the control plate points towards the air filter side of the carb. Then just re-attach the butterfly plate so it sits as it did before it was removed. I used blue loctite when tightening them down. 

Not a horribly hard operation. Just a bit tedious when trying to get the butterfly screws out without stripping the heads. 

 



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A thought about the screw heads: Since these are Chinese built, could the heads be the JIS (Japanese Industry Standard) instead of American? They are slightly different, and not entirely interchangeable as far as screwdriver bits go. That is why most Japanese motorcycle bolts are buggered up when worked on by American mechanics.

 

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I dont know. Just figured one of the junk Chineese screwdrivers I have would fit the Chineese screws666

 

These screw heads are no terrible. They actually have more area to grab than the ones on an oem Kohler carb. Wrecked plenty of those screws myself. I had the right screwdriver(bit) in this instance and they came out good. Just a matter of applying enough downward force on the screw and turning slow enough to notice whether the screw is turning or the driver is slipping.

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