I just went through my 7 year old Walbro catolog and here is the list of Wt carbs with accelorator pumps, and hi and low needles and no primers.
12.7 mm
Wt 513-1 There are a few smaller ones listed also. motorhd
Wt 537-1
13.49mm
Wt 171-1
Wt 172-1
Wt 228-1
Wt 451-1
Wt 480-1
Wt 540-1
Wt 542-1
Wt 555-1

Thanks. You didn't happen to jot down the 11.1mm carbs with accel. pumps did you?

You missed WT-610-1. I will try to find my short list of HDA (15mm and up) with accelerator pumps to post.

AV8TOR

These are the rest of the WT Walbro carbs with accelorator pumps.

6.5 mm with fuel pump return spring (4 stroke) WT 366-1 WT 456-1

7.95mm WT 37-1 WT 424-1

9.53mm WT 35-1 WT 38-1 WT 204-1 WT 357-1 WT 367-1 WT 381-1 WT 385-1 WT 417-1 WT 449-1 WT 450-1

11.11 mm WT 29-1 WT 356-1 WT 358-1 WT 464-1 WT 516-1 WT 517-1 WT 527-1 WT 613-1

Thanks guys,
I gave been looking through the Walbro data for thos carbs, but without very much luck.
The acc. pump probably is the answer to a lot of prayers.

I just found out that you have to add the dash after the WT before the number to get Order Tree to recognize the number. eg, WT-456-1
(WT 456-1 won't work)

QUESTIONS:

1. How do you get the plugs (item 11 on the illustrated parts diagram) over the needle out so you can adjust the needles.

2. Also, just what is a typical part number for the accelerator pump, on say the WT-456-1 carb?

3. On a carb with only the low needle, can you drill and tap the housing for a high speed needle?

Thanks

1. The WT-456-1 doesn't come with limiters? I've seen the plastic limiter caps on some carbs but I cut them off with a knife.

2. The carb body has to be made for the accelerator pump from the beginning. You cannot add one to a carb with no accelerator pump

3. Normally no because of the machining required. (Threads and the needle seat)

Thanks for the tip on the dash in the carb number.
There is no ryme nor reason to the Walbro carburator numbering system. It looks kind of chronological . The only way I can tell is to look at the parts listing for each carb and see if the accelorator pump part number is listed there.
motorhd

The 456 I received recently has limiters.

Who-hoo! I've been looking for a list like this.

Thanks,
Scot

I just googled Zama and went to several zama parts lists and made a list of various sized carbs with accelerator pumps. They have quite a few with accelerator pumps.
It is generally accepted here that Zama carbs are not so good for our purposes.
Perhaps we should give the Zamas another try.? I suspect there are a lot out there.
motorhd

The biggest problem with the Zama's has been documentation.

If you can organize a comparison it would be great

It was not a WT-456 that I have, and I will have to check the number, but, I have a walbro with large venturi, choke and maybe a fuel pump return spring, but, it has metal plugs over/instead of low and power needles. Can they be removed and are there needles under them? I have other carbs with just a low needle and a undrilled cored partial hole where the high needle would be. I understand they cannot be drilled and tapped for a needle. TIA

I guess you do not have anything to loose with those carbs with the blocked needles?

Drill a hole in a plug and pry it out and see what you have.

I've never done it but I've heard that some just have an orvice under the plug. At one time some models had a screw under the plug that you could adjust

I say that you have nothing to loose because a carb without two needles just will not work for model use.

I agree with that. Probably there is just a fixed jet though. Those carbs are made for very specific engines under very specific load, so they can comply to CARB (California Air Resource Board) regulations. Pun anyone?
The idle needle will influence the whole throttle range, but there is no way of adjusting the delicate balance between idle and high speed jetting, so intermediate throttle settings will be lacking at best.

Thank You
so much for this list. Ijust found out that the wt-456-1 I ordered is backordered 2-4 WK.
Did any one try to use one of those 7.95 mm ventury on a 4 stroke20cc?

Thank you
Adrian

WT-37-1 is no longer available.
I did find a new one on ebay $35.

Adrian

Hi,

Did you find that list with acceleration pump carburators.

Adrian</p>

Look at post no. 3 in this thread.

It would be nice to know about smaller sizes like the 11.11mm carbs

See post # 2 last line is 11.11 wt carbs

Thanks, for some reason or another I missed that

I think it was Post no. 3, as I said.

Sincerely,

Richard

There was something else going on at my house besides RCU and I looked at post #1 and forgot about #3

Jim, When I have that problem, my wife calls it old age. LOL

motorhd, Thanks for the list.

Glad to help, these accelerator pump carbs have solved a lot of tuning problems for me .