Kohler K91 carburettor.

[chris sutton 610]

Ive got a couple of Kohler K91s that won’t run, I’ve removed the carbs to clean and overhaul them and see some cheap new ones on eBay.

Has anyone used these or had any experience with them ?.

I’ve  heard there from China but are cheaper than buying rebuild kits. 

[ebinmaine 69,346]

My advice would be to buy a soak kit if you don't already have one.

 

Use rebuild kits on original Kohler carbs..

 

 

Several of us have used the Chinese repop carbs and had good luck.

 

 

I CAN'T recommend them.

 

 

I bought one clearly and correctly listed for a K341.

It was a very small bore.

It also didn't ever get to run quite right.

I disassembled and cleaned it when new. (I find it ridiculous to be doing this to a "new" carb.)

Then did that 2 more times within a month or 2.

One day it just started raining fuel out the front.

Obviously float stuck wide open.

Disassembled and found black grains in the bowl.

 

The tank and fuel pump were clean.

The lines and see through filter were new.

 

 

It's in the recycling facility now.....

 

You may be a lucky one but.... 

[WHNJ701 4,165]

you get what you pay for,  they are garbage carbs.  rebuild your oem ones

[The Tuul Crib 7,338]

2 hours ago, ebinmaine said:

My advice would be to buy a soak kit if you don't already have one.

 

Use rebuild kits on original Kohler carbs..

 

 

Several of us have used the Chinese repop carbs and had good luck.

 

 

I CAN'T recommend them.

 

 

I bought one clearly and correctly listed for a K341.

It was a very small bore.

It also didn't ever get to run quite right.

I disassembled and cleaned it when new. (I find it ridiculous to be doing this to a "new" carb.)

Then did that 2 more times within a month or 2.

One day it just started raining fuel out the front.

Obviously float stuck wide open.

Disassembled and found black grains in the bowl.

 

The tank and fuel pump were clean.

The lines and see through filter were new.

 

 

It's in the recycling facility now.....

 

You may be a lucky one but.... 

100%

[Mike'sHorseBarn 3,036]

Have you checked to see if you're getting spark? Spray some carb cleaner into the carb and give it a couple pulls and see if it pops off or not. If it doesn't, more times than not you don't have spark.

[pfrederi 18,090]

4 hours ago, ebinmaine said:

My advice would be to buy a soak kit if you don't already have one.

 

Use rebuild kits on original Kohler carbs..

 

 

Several of us have used the Chinese repop carbs and had good luck.

 

 

I CAN'T recommend them.

 

 

I bought one clearly and correctly listed for a K341.

It was a very small bore.

It also didn't ever get to run quite right.

I disassembled and cleaned it when new. (I find it ridiculous to be doing this to a "new" carb.)

Then did that 2 more times within a month or 2.

One day it just started raining fuel out the front.

Obviously float stuck wide open.

Disassembled and found black grains in the bowl.

 

The tank and fuel pump were clean.

The lines and see through filter were new.

 

 

It's in the recycling facility now.....

 

You may be a lucky one but.... 

 Eric where did you get the K341 carb from?  i got one from I save old tractors put it on an newly overhauled engine could not get it to run smoothly.  Took the original which happened to a Walbro fixed jet rebuilt it and the engine runs just fine....

[ebinmaine 69,346]

2 minutes ago, pfrederi said:

 Eric where did you get the K341 carb from?  i got one from I save old tractors put it on an newly overhauled engine could not get it to run smoothly.  Took the original which happened to a Walbro fixed jet rebuilt it and the engine runs just fine....

This one didn't come from there. It was just an eBay purchase. I checked the ratings of the company and they were good but I had no real information on the carburetor itself.

After I took it apart for the third time I just left it off. That was actually when I noticed the real difference in the bore size being substantially smaller.

 

[clueless 3,027]

Over the past few years I've bought four of them, two work great, two not so much. 

[bottjernat1 2,190]

I would recommend rebuilding what you have they are easy. I have a couple k91's. But i have also bought the cheap aftermarket carbs and i have never had an issue. but like the folks above said it can be a hit or miss on the overseas stuff.  amazon has this kit! https://www.amazon.com/KOHLER-25-757-01-S-Carburetor/dp/B0015MLUS8/ref=sr_1_3?keywords=kohler+k91+carburetor+kit&qid=1579878412&sr=8-3  or this one https://www.amazon.com/KIPA-Carburetor-Rebuild-2575701-S-2575701/dp/B07676ZCTK/ref=sr_1_4?keywords=kohler+k91+carburetor+kit&qid=1579878476&sr=8-4

Edited January 24, 2020 by bottjernat1

[Achto 28,080]

1 hour ago, Mike'sHorseBarn said:

Have you checked to see if you're getting spark?

 

 Also set your points gap using the static timing process. .002" took my hard to start K91 and made it into a one pull wonder.

[bottjernat1 2,190]

What acho says but i believe the gap is .020

[bottjernat1 2,190]

Here is the gap cart it is the same for most of the old kohlers. I even set my old 16hp onan on the sear i use to own at that. 

[wallfish 17,141]

Points gap seems to be very touchy on K91s compared to other size engines. Don't get stuck on that .020 setting.

What Dan @Achto is referring to is the .002 change he made to the gap by doing a static timing procedure and not the initial setting of .020. Very very slight changes to the gap on these K90-91 engines can make a big difference. I've had some which are clearly more sensitive to it than others so it's a good place to start.

[Achto 28,080]

6 minutes ago, wallfish said:

Very very slight changes to the gap on these K90-91 engines can make a big difference

 

Thanks John, I guess I should've explained myself better. At .020" points gap my K91 was a PITA to get started, didn't matter if it was warm or cold. After setting them using the static timing method the points gap ended up at  .022". Now most of the time it only takes one pull to get it started, warm or cold. 

[wallfish 17,141]

Have ended up at .018 too

[lynnmor 7,446]

A .002" variation in points gap should only make a slight difference in timing.  I believe that there are other issues and that small gap change was not significant.  If .002" would be a big problem, then there would be a mountain of engines that don't run.

[chris sutton 610]

Thanks for all your replies, both engines have good sparks. one engine fire's and one ran briefly with gas squirted in the carb

I was looking to buy rebuild kits and noticed the Chinese carbs half the price of the kits.

[953 nut 56,432]

6 hours ago, wallfish said:

Points gap seems to be very touchy on K91s compared to other size engines. Don't get stuck on that .020 setting.

What Dan @Achto is referring to is the .002 change he made to the gap by doing a static timing procedure and not the initial setting of .020. Very very slight changes to the gap on these K90-91 engines can make a big difference. I've had some which are clearly more sensitive to it than others so it's a good place to start.

Your K-91 will not have the ACR Camshaft. This timing information should be helpful to you.

Ignition timing on Kohler engines.

 

Gapping the ignition points at .020 has always been the standard answer to how points should be set. That probably will get you into the ballpark where the engine will run, but with a bit of additional effort you can improve the engine’s power and performance.

The Kohler engine manual in the Red Square files section covers two methods for setting the ignition timing, Static Timing and using a Timing Light. This manual is a relatively new manual and it overlooks the fact that many of our engines were built prior to the ACR (automatic compression release) camshaft.

Earlier engines (mostly 1965 and earlier) had a Spark Advance camshaft that can not be timed using Static timing. At rest (and very low RPMs) the timing is retarded to fire slightly after TDC. The timing mark (SP) on your flywheel is at twenty degrees before top dead center but at rest the points on these engines break about ten degrees after top dead center. The only reliable way to check or set the timing on these engines is with a timing light.

 

[wallfish 17,141]

Like others, I've had good and the bad when it comes to those repop carbs on Kohlers.

Flip a coin is the best way to decide!

90% of the time a good thorough cleaning and just a bowl gasket works for me. Then do final needle adjustments.

On Tecumseh, I just order a repop.

 

[Achto 28,080]

1 hour ago, chris sutton said:

Thanks for all your replies, both engines have good sparks. one engine fire's and one ran briefly with gas squirted in the carb

I was looking to buy rebuild kits and noticed the Chinese carbs half the price of the kits.

 

Sorry Chris, we got a little I can not speak for the Chinese carbs.

I have always had good luck rebuilding the original carbs. I purchase a Kohler rebuild kit, which contains mainly a needle & seat and gaskets. Remove all parts and make sure they are clean, clean, clean, pay close attention to the emulsion tube. make sure that air can pass through all of the holes. If the throttle shaft feels sloppy in the hole, add a 7/16"o.d. x 1/4" i.d. x 1/8" thick bushing to remove the slop & seal the shaft to the body of the carb.