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WYL Carburetor Adjustments

#1

L

lindylex

I have the following carburetor WYL. It is from a Troy-Bilt backpack blower. I can not find where the carburetor adjustments are for high and low. It seems the closes is the adjuster screw for idle. I rebuilt the carb and it idles but when I press the gas it cuts off. I need to adjust the carb to get it to not fall on its a$$.

Thanks

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#2

B

bertsmobile1

This is an EPA compliant carb
There are no adjustments apart from the throttle stop .
If you used carb cleaner to blow through all of the orrifaces then better than average chance you have buggered up the check valve.
The other biggie is the main jet falling out
Neither part is available so unless you botched the rebuild then it is new carb time


#3

L

lindylex

bertsmobile1 said:
This is an EPA compliant carb
There are no adjustments apart from the throttle stop .
If you used carb cleaner to blow through all of the orrifaces then better than average chance you have buggered up the check valve.
The other biggie is the main jet falling out
Neither part is available so unless you botched the rebuild then it is new carb time
Click to expand...

"If you used carb cleaner to blow through all of the orrifaces then better than average chance you have buggered up the check valve." this is what I did.

Is there a carb that fits this that is adjustable?


#4

B

bertsmobile1

Most likely not.
The rotary valve carbs are needle jet carbs.
If you look closely at it you will see that the rotary valve lifts up as it rotates.
That raises a tapered needle that goes through the main jet.
This is how the high speed fuel supply is regulated..
Some have a screw right down the middle through the top and this changes the position of the needle with respect to the position of the throttle valve which is the same as raising or lowering the needle on a slide carb as fitted to old motorcycles.


#5

Scrubcadet10

Scrubcadet10

WYL Carburetor at DuckDuckGo

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#6

L

lindylex

bertsmobile1 said:
Most likely not.
The rotary valve carbs are needle jet carbs.
If you look closely at it you will see that the rotary valve lifts up as it rotates.
That raises a tapered needle that goes through the main jet.
This is how the high speed fuel supply is regulated..
Some have a screw right down the middle through the top and this changes the position of the needle with respect to the position of the throttle valve which is the same as raising or lowering the needle on a slide carb as fitted to old motorcycles.
Click to expand...

I did a pressure test and the carburetor holds pressure from the primer bulb and the fuel intake side.

In this photo https://www.lawnmowerforum.com/threads/wyl-carburetor-adjustments.57889/#lg=post-349810&slide=1

Is this bronze looking recessed thing what I can screw in or out to adjust the fuel mixture for high? From the looks of the diagram of the carburetor I think it matches what you are describing. My next step is to widen the main jet by drilling it out to a wider diameter. I am trying to see what is possible before modifying the carburetor.


#7

AVB

AVB

Yes provide it is not EPA plugged. It should be a micro D shaped version; unless, they changed it again. Of course I am used to Echo using the plugs on the Zama carbs.


#8

L

lindylex

This is fixed. I had to widen the passage for the fuel via the main jet by using a very small drill bit and a pen vise to hold the drill bit and open the hole a little. It works fine, blows well and does not fall on its face. It was an easy repair once I knew what to do.

Hope this help someone.


#9

B

bertsmobile1

thanks for the follow up.
Most likely the main was gummed up from modern fuel.
Right now you are coming into season over there so it will be fine but whenever you look like not using it for a month or more tip the fuel out and run the blower dry .


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