Wanted, Carb information.

[Powerstroke Cowboy]

I have a string trimmer apart right now and was planning to do some port work for a little more power. Before I started porting I figured I better check the carb to make sure it not one of those new fangled no adjustable thing. It is not adjustable. So I am needing help to see if there an adjustable carb that's a direct swap.

In should be able to, in theory, drill out the high speed jet for more fuel as needed. But the chance of getting it nailed correct would be almost impossible, for me that is.

It's a Walbro barrel (if barrels the correct term) carb. Here's some picture of the carb, plus picture of the numbers on the carb. If you need more information or pictures, ask and you shall receive.

Thanks for any and all help.

 

[Powerstroke Cowboy]

Close up shot of the last pictures letters and numbers.

 

[backhoelover]

This is your adjustment, if I remember correctly there is a little brass jet in carb that pressure into main body held in with a oring. You might can drill this out if needed but idk

 

[Powerstroke Cowboy]

This is your adjustment, if I remember correctly there is a little brass jet in carb that pressure into main body held in with a oring. You might can drill this out if needed but idk View attachment 370799

Thanks for the reply. As far as I can tell, that is the low speed adjustment. Am I mistaken on that?

The picture attached is generally where the high speed screw is. But it's just a brass plug. I did drill this plugout and there was no screw behind it. Just a hole that let gas through. I will take a picture and post it up.

 

[Powerstroke Cowboy]

@backhoelover

More pictures with the brass plug out.


In this picture you can see the hile that let's gas through.


In this picture (it's hard to tell) it looks like there another cap/plug pressed in.

 

[backhoelover]

idk what that is. Have to take the carb apart to see other jet taking it apart will help you understand fuel flow

 

[Powerstroke Cowboy]

idk what that is. Have to take the carb apart to see other jet taking it apart will help you understand fuel flow

So, here are some more pictures. The thing that looked like a plug ended up being this.


You can see it sticking into the barrel of the carb.

 

[Powerstroke Cowboy]

@backhoelover

The barrel or whatever you call the part that sits in the bore of the carb pushes on the part that sticks into the bore. There is no fuel gallery that is controlled that I could fine by the small end of the sliding piece. The only thing it does is change the volume between it and the plug I drilled out. Maybe that some how changes gas flow through the main jet?

Either way itis not adjustable. The only way that I can see to get more fuel would be to drill out the main jet.

Here are some picture of the carb barrel. When the barrel is in the Idle position that piece sticks Into the bore of the carb. But as the barrel open it pushes that piece back into the port behind it. You can see in the picture where it rides on the barrel.
Here is a picture of a 13 dollar nock off from the PRC. I am tempted to buy it and see if maybe their's is adjustable.

 

[backhoelover]

That a accelerator pump

 

[backhoelover]

Pull the carb apart. There is a fixed jet that feed the rotor nozzle. It pressed into the main body under the diaphragm plate

 

[Shane¹]

@backhoelover

The barrel or whatever you call the part that sits in the bore of the carb pushes on the part that sticks into the bore. There is no fuel gallery that is controlled that I could fine by the small end of the sliding piece. The only thing it does is change the volume between it and the plug I drilled out. Maybe that some how changes gas flow through the main jet?

Either way itis not adjustable. The only way that I can see to get more fuel would be to drill out the main jet.

Here are some picture of the carb barrel. When the barrel is in the Idle position that piece sticks Into the bore of the carb. But as the barrel open it pushes that piece back into the port behind it. You can see in the picture where it rides on the barrel.View attachment 370844View attachment 370843
Here is a picture of a 13 dollar nock off from the PRC. I am tempted to buy it and see if maybe their's is adjustable.
View attachment 370846

I have a carb like that I ordered for the gas tank grommet but never put it on because ran so good with the original but I could put it on and see if it is adjustable at that screw

 

[Powerstroke Cowboy]

I have a carb like that I ordered for the gas tank grommet but never put it on because ran so good with the original but I could put it on and see if it is adjustable at that screw

That would be nice to know. But, don't go through all that trouble on my account. After seeing what @backhoelover said, I bet thats just a screw in plug.

would you be willing to pull that screw/plug out and see whats behind it?

That a accelerator pump

Okay, learn something new every day.

Thanks!!

Pull the carb apart. There is a fixed jet that feed the rotor nozzle. It pressed into the main body under the diaphragm plate View attachment 370881

I did pull it apart yesterday afternoon for all those pictures. I Did see the jet your talking about. It got 34 stamped into it. That's the main jet. I could drill it out. But, that's just a shot in the dark for me.

 

[Shane¹]

I will try to dig that carb out later

 

[Powerstroke Cowboy]

I will try to dig that carb out later

That would be awesome.

 

[backhoelover]

Check this out

 

[backhoelover]

Sorry wrong one you need one with primer

 

[backhoelover]

Here is wyl, this will help with understanding carb

 

[Shane¹]

I am assuming high speed adjustment

 

[Powerstroke Cowboy]

I am assuming high speed adjustment View attachment 370990

Is the needle a solid shaft from the tip to the head? It's a blury picture so hard to say. But that looks like a high speed screw to me. Thank for the picture and help!

@backhoelover . That is good information! Thank you for sharing it. That could be handy. By that diagram what I thought was the main jet, is the main jet.

If I can fund a carb that has and adjustable high and low speed screw, I would be set to mod this thing and fell good about it.

 

[backhoelover]

Yes the rotary carbs don’t hand idle circuit like a typical butter fly carb. Everything is feed from the center nozzle