HOW TO INSTALL ADJUSTABLE FUEL NEEDLE IN KOHLER COMMAND CARBURETOR

(Much of the information contained in this document is courtesy of Merv. Thanks for the help.)

(Updated: 5/24/2004. Updated items in blue)

1.)    This procedure is done at your own risk. I make now guarantees of the operation of the Carburetor once this procedure is done. This is for informational purposes only. MODIFY THE CARBURETOR AT YOUR OWN RISK.

2.)    This modification should be done during a carburetor rebuild as drilling of the main jet area WILL leave shavings in the fuel bowl and in the main jet area. DO NOT ATTEMPT TO DRILL AND INSTALL NEEDLE WITHOUT CLEANING MAIN JET AREA AND FUEL BOWL AREA.

ON TO THE INSTALL

<Picture of Stock Kohler Command Carburetor. Choke Plate and Rod have been removed as well as the Throttle Plate and Rod. Removal of Choke Rod and Plate and Removal of Throttle Rod and Plate are not necessary for the Install process>

NOTE: If you plan to remove the choke plate and shaft, you will need to plug the holes where the shaft originally was located. Use blue or black RTV Sealant. Let the RTV setup and remove any excess that might be in the Throttle bore area (air passage). You want to keep the air way as clean and smooth as possible.

1. Remove Fuel Shutoff Solenoid (Labeled as 1) in photo below)

2. Remove Fuel Shutoff Solenoid Brass Fitting (Labeled as 2) in photo below)

(Label 1) is the Fuel Shutoff Solenoid, Label 1a) are the Screws that fasten the Fuel Shutoff Solenoid to the Carburetor, Label 2) is the Brass Fitting)

Brass Fitting Has 2 Rubber O-Rings. May require the use of pliers to remove from Carburetor. If pliers are needed, grip by the outside Brass ring and twist as you pull out.

(Photo below shows the Carburetor with the Fuel Shutoff Solenoid and Brass Fitting Removed. Brass Fitting is on the Left and the Screws to the are for the Fuel Shutoff Solenoid).

3. Drill and Tap threads for Adjustable Fuel Needle.

(Photo of TISCO #71-28 Adjustable Fuel Needle. Can be purchased at local Farm Implement Dealer)

If you have troubles finding this part, http://www.ankenytractors.com. E-mail them and give them the part number (TISCO #71-28). Local Farm Implement Dealer in Ankeny, IA. They will have to order the part but usually takes a couple of days.

NOTE: This is the same part that is used to change the Kohler #26 and #30 carburetors to a bottom adjustment as well.

Drill Area where Fuel Shutoff Solenoid Brass Fitting was located. Will need to drill using 5/16" drill bit. Be careful with this part. You need to get a good clean straight hole made using the 5/16" drill bit. Remember, this is soft aluminum you are drilling in (I personally used a 19/64" Drill Bit on my 2 Carburetors). You will only need the drilled area to go just past the fuel bowl opening in the Main Jet hole (Approx. 1/2" - 3/4" Deep).

(Photo Below Shows Carburetor bottom half with Main Jet area drilled to 5/16")

Next, Tap 3/8" Fine Threads

NOTE: This is very critical to get the Threads straight. Having the threads straight will allow the point of the needle to properly align and bottom out inside the Main Jet. If the Threads are not straight and properly aligned with the Main Jet opening, the Needle will not function properly.

Again, you are tapping into Aluminum so be careful.

(Photo Below shows the Tapping of the Threads)

(Photo below is the Carburetor bottom with the Main Jet Hold drilled and tapped with 3/8" Fine Threads with the Main Jet Needle Adjuster setting next to it.)

4. Install the Needle

Simply Screw in the Needle Adjuster (Note: Do not over tighten the into the Alum and strip out the threads. The Adjustable Fuel Needle will only be held in by a few threads so be careful.)

(Photo below shows the finished needle in the bottom of the carburetor.)

Note: When correctly done, the needle adjuster (T-Handle) will be screwed in almost all the way in (almost all the way to the tightening nut, smaller nut in photo. Approx. 1/8" from top of small nut) when needle point is seated (or bottomed out) in the Main Jet.

When doing the final install, use some Teflon tape (pipe dope) around  the threads to ensure a good tight seal around the Main Jet Nut and the Carburetor bottom. If not done, fuel can leak out this and cause a big mess.

Stock Kohler Command 18hp Jet Size (sizes very depending on the application they were initially intended)= 1.52mm (approx 0.059")

Stock Kohler Command 25hp Jet Size (sizes very depending on the application they were initially intended)= 1.75mm (approx 0.068")

Note: Start with a small jet and work your way to a bigger jet.

Also, do not accede 0.080" Main Jet opening. Doing so may make it impossibly to lean out the carburetor enough for proper operation. I personally am running a Jet opened up to 0.073".

(NOTE: For purposes of having the Adjustable Needle threaded into more of the Cut Threads, the original area where the Brass Fitting was pushed in could be ground down. I have not tried this but do not see any reason that it could not be down to get more of the Threads to hold.)

Removing Fuel Shut-Off Solenoid Boss (New 5-24-2004)

for allowing more threads on Adjustable Needle to grip to carb.

You will want to remove the alum. boss that was originally where the fuel shut-off Solenoid Bass Fitting was pressed into (area is noted on photo). You will remove approx. 1/8" of alum. This will allow the adjustable Needle Assembly to grip more of the cut threads. 

(Note: The White substance in the photo is dried Pipe Dope from a carb that already had an Adjustable Needle Assembly installed)

Photo Below Shows Bottom Half of Command Carb.

Photo below shows Bottom Half of Command Carb after Fuel Shut-Off Solenoid Boss has been filed down and O-Ring Groove eliminated.

Note: Be Careful and Remove Even Amounts across the Shut-Off Solenoid Boss. Take your time on this and remove small amounts at a time. A Flat File works best for this. Use short even pressure strokes to remove the material..

After doing this, you will want to use forced air of some kind to blow off all the small Alum. Shavings from the flat file.

(Note: See Notes on Photo for detailed instructions)

Photo below shows a view from the bottom of the Command Carb after the alum. has been removed.

(Note: See notes on the Photo for detailed instructions)

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Photo below shows the view from the bottom of the Command Carb after the alum. has been removed and the adjustable needle assembly has been installed.

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Photo shows view from the top of the bottom half of the Command Carb.

(Note: The pictures below show the adjustable needle bottomed out in the High Speed Jet. Note the difference between the distance the T-Handle sticks out when you have removed the O-Ring Groove Compared to when the O-Ring Groove is Not Removed.)

O-Ring Groove Eliminated           O-Ring Groove Left

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