walbro wy carburetor

ggoyenecheSeptember 24, 2005

Anybody familiar with the Walbro WY carb?

This one is used on a Tanaka TCB-160 weedeater. I've got symptoms of lean mixture or starvation but can't seem to find cause.

Fuel flow from tank the carb is OK and I replaced fuel hose. Fuel pickup in tank is OK and flows well. On disassembly, inlet diaphragm and valve are OK, as is inlet screen. Pumping flapper valves are also OK and main jet which is fixed design is also clear.

Carb does not have idle and main mixture screws that I am familiar with on other Walbro's and Zama's. Also has a cam arrangement which lifts the throttle bore and would appear to raise a needle in the main jet. There is an adjustment on top of throttle, but I'm not sure how it works.

I'd appreciate any insight from someone familiar with this particular carb. Spare me general advise such as "spider in the fuel cap", etc. However would appreciate information specific to this Walbro.

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Sounds like you have the carb real clean. Would look for a air leak somewhere, seals, gaskets, boot if it has one. Even if it's not adjustable it used to run ok the way it was so it would be a air leak or dirt, something like that . Steve

    Bookmark   September 24, 2005 at 9:00PM
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arceeguy(z6 NJ)

I'm not familiar with the engine or carb, but I have pulled my hair out on other 2 stroke engines with similar symptoms. After cleaning or rebuilding carbs and still having issues, it turned out to be the cylinder to crankcase bolts that had backed out a little, causing an air leak and the lean mixture. It's a long shot, but check the cylinder mounting bolts and backplate screws if applicable.

Good Luck!

    Bookmark   September 24, 2005 at 11:55PM
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I've had the intake manifold bolts vibrate loose from the engine & cause an air leak.

    Bookmark   September 26, 2005 at 3:55PM
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The diaphragm that drives the needle valve mechanism can look perfect but be stiff and cause the problem.

    Bookmark   September 27, 2005 at 9:27AM
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wise_guy(NW MN)

It sounds like it is a rotory valve type carb. It is not uncommon for the little wheel -- that lifts the valve as you open the throttle -- to wear out and cause your mixture to be lean. That "adjustment" on top of the throttle is just a bolt that removes the throttle plate. You will have to go to a distributor and have them look up the parts and explain them to you. Usually the wheel that lifts the valve is plastic and the valve is plastic. If your fuel intlet needle height is right and everything else is clean, you'll likely have to replace the rotory assembly.

A test: while weedeater is running, pull throttle plate outwards (it's on a spring holding it in). As you pull it out, you are enriching the mixture. This should cause the engine to suddenly run fine.

    Bookmark   September 27, 2005 at 12:38PM
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hlw49(Z6 TN)

What is the completer model no. of the carb? So we can look it up and know more about of the carb. Later Butch

    Bookmark   September 27, 2005 at 8:45PM
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wise_guy(NW MN)

No response....

No really, I worked at a golf course at my last job. We had about a dozen trimmers with this style of rotary/slide valve carb. If you have checked everything else, I am almost positive this is your issue.

The original carbs had a plastic wheel that ramped the rotary valve outwards, which increased the area available in the main nozzle, as you opened the throttle. The new rotary assembly should come with a metal wheel.

I tried to find a place where you can order the rotary assembly online, but came up empty handed.

    Bookmark   September 27, 2005 at 9:02PM
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hlw49(Z6 TN)

Part # is 34-530 and list for $11.09 if you can find it. None of the people we deal with have it either. Later Butch

    Bookmark   September 27, 2005 at 10:35PM
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I am having a similar problem with a Walbro on a 12.5 Kohler. I realize that the engines and carbs are completely different but if you find someone knowledgeable I would love to talk with him or her. Thanx.

    Bookmark   August 28, 2006 at 7:16AM
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I found a PDF file ebook manual for the Walbro WY carburetor online that will help you, they also have a lot of other small engine carburetor manuals


Here is a link that might be useful: Walbro WY Carburetor

    Bookmark   August 3, 2008 at 11:30PM
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HI i have been reading the forums above the problem i have is i can't get the plastic top part of the carb of it's a walbro wya carb there seems to be a brass cup in the centre anyone know how they come apart i'm afraid i might break it

    Bookmark   September 27, 2008 at 3:13PM
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I have a Walbro WY on a Husqvarna 22R trimmer. During use it flooded out and quit. A new kit (K-10-WY) did not help....nor taking it apart several times being sure all parts were in proper order. Also, pulling the starter rope pushes even more gas into the piston chamber. When everthing is dried out it starts right away but almost instantly floods out. Help!

    Bookmark   July 16, 2011 at 6:15PM
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Wayne, For the sake of learning and informing others, were you able to cure your Walbro WY flooding woes? If you did, do you remember what the culprit was?

    Bookmark   November 8, 2011 at 7:00PM
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