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Brent_Baumer

Is this a Walbro Carb? What is wrong with it?

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Brent_Baumer
Hi all. I have a "late" Kohler model K341 replacement from Small Engine Warehouse. This carb was on it. Although it is similar to the roughtly 6 other K341 carbs I have or have had it is NOT the same. Construction and location of needle valves are different than all the others which were/are identical.

After spending 3 weeks trying to figure out why the tractor would run good for 30 seconds then sputter, 30 seconds then sputter and on and on and replacing every ignition component and removal, disassembly cleaning and adjustment of this carb at least half a dozen times I finally installed a different carb off another much older K341. The old carb cured the problem instantly. The throttle shaft has no play and I am certain through the use of Permatex it is not sucking air past the gasket. The cyclical sputtering occurs under load and at no load. The other thing about this carb is that the engine is extremely sensitive to the high speed mixture adjustment. You don't even have a full turn between too lean severe sputtering and too rich severe sputtering. Really not much more than half a turn. Any thoughts?

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Salthart
Try putting a timing light on the engine with that carb installed and looking down the bore of the carb using the timing light. There are a few things that can cause that problem. More than likely its 2 problems in one.. A high speed jet thats "Gummy" and a float thats either to high or heavy ( Fuel inside it ) . If it is a float problem, you should be able to see Droplets of fuel going down the intake.

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Brent_Baumer
I have adjusted the float tab to the point it leaks and to the point it is closed with the smallest amout of fuel. I have not noticed the float itself getting filled with fuel. I don't know how the high speed jet could still be gummy after nearly 2 cans of Gumout wasted on this thing.... Thanks for the tips though.

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RonT
Brent, Try blowing compressed air through all of the ports on the carb while cleaning it. Remove all of the needles, screws, and jets while cleaning don't just do one at a time. Also I would not use any gasket maker/sealer on a carb gasket but that is my thought. Sometimes 1/8th of a turn will make a big diffrence in a poor running motor. So 1 turn may be ok for adjustment.

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maxtorman1234
I had a kohler carb that did something similar to that, I dissasembled it several times and cleaned it and it didn't help. It had sat for years before I got it and the gas was gummy. I eventually tried spraying some gunk in it, and sat the carb facing down. I saw stripes from the dirt and junk come out of a few of the small holes in the carb, and now it seems to work good.

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HubbardRA
I had a carb similar to that on a Tecumseh 10 Hp. It did an oscillation that I couldn't adjust out of it. Finally one day a friend of mine looked at it and told me the throttle stabilizer spring was broken. This was a small spiral spring that was wound around the throttle shaft. It is there to put a small amount of force on the throttle to keep it from oscillating during operation. It did the same think as the long spring that fits over the governor link on some B/S engines. Basically keeps all of the slack out of the throttle/governor linkage to keep vibrations from moving the throttle shaft in the carb. You might want to see if this carb has one that is broken. Can't tell from the picture. Replacing the spring fixed the problem on the Tecumseh. You could also try putting a small, light spring on the linkage to eliminate any clearance in the link system and see if this helps.

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TimJr
Just throw away that Walbro carb. They (in my opinion) do not perform as well as the other style which is commonly referred to as the Kohler carb. I think those were actually made by Carter - can anyone verify that? I have had tuning problems with those Walbro's - even a couple of new ones out of the box. The most trouble seems to come on a used engine that may be lacking a little vacuum etc., but it seems the Walbro has a much narrower band of adjustment, and is hard to cover all RPM's. Granted, any dirty or misadjusted carb will not perform as desired. Always clean carbs with a good brand of carb cleaning solution - don't rinse it with gas - it won't cut through the varnish, plus it's more dangerous. Tim

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powerking_one
Brent, I would have to agree with TimJr on this one. My Walbro LME with a fixed main jet on my Tecumseh OH-160 ran terrible at rated high RPM's until I swapped it out for a fully adjustable earlier version. Carter (venerable earlier Kohler versions) equipped engines always adjusted and performed beautifully. I think Walbro for Carter replacements in general are roachy substitutes. Tom(PK)

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Salthart
Brent, Sometimes spraying just isn't enough. Around home we have a wasp we call a dirt dauber. They range in size from the size of a BB to almost as large as my pinky. They pack dirt into small holes and carbs are not imune. There are air bleed vents in most all bowl type carbs and if clogged they can give you a fit. As fuel is drawn out the pressure in the bowl becomes lower thus making it harder for more fuel to leave.This will ease up as the float allows fuel in and ups the pressure. Did you remove the welsh plugs and check for clogging under them ? I can't build your carb for you over the net nor can I see all that you have done. I can only put forward what I would do if it were in my hands. PM me for my addy...Send it with a welsh plug kit and I'll build it for you no charge. BTW, to check and see if the spring idea ( or governor adjustment for that matter ) is right, hold the throttle still by hand.. If the trouble is in linkage or the gov, it will smooth up.

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Brent_Baumer
Thanks for the offer Marty. Since the machine is running good now with an old carb this is kinda on the back burner. I did find out (by looking a little closer at the casting) it IS a Walbro. I'll likely take it apart one more time myself and COMPLETELY and thoroughly go through it again looking for some of the things suggested. Thanks again, Brent

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