All Day Dan

My Feedback: (5)

The Walbro WT-76-1 carburetor now comes with a spring loaded choke instead of the manually operated detent version. Is there a version of the WT-76-1 that still uses the original type of choke? Has anyone converted one of these new chokes back to the older type? Dan

w8ye

My Feedback: (16)

IIRC the WT-76-1 always did have a spring loaded choke.

You can remove the spring?

Or use a positive remote linkage on your choke for a positive lock each way.

Or buy a carb from DA?

av8tor1977

My Feedback: (6)

It is a little tricky to do, but I have many times disassembled spring loaded chokes, ground a relief on the choke shaft with a small ball shaped cutter in the Dremel, and added the little ball and spring to create a detent style choke.

Two tips: 1. Be sure to grind the swaged screw end off the choke plate screw before removing the screw or else you'll ruin the brass choke shaft when you take out the screw. 2. Be really sure to clean the choke shaft and the screw and use Loctite on them when re-assembling the choke. (Don't let the Loctite wick down into the choke shaft bores or you'll have a permanently stuck choke.)

AV8TOR

Truckracer

My Feedback: (19)

I have no experience with the WT-76-1 but quite a bit with the WT-76, WT-76A and WT-76B. These last three all have conventional chokes. I watch *Bay regularly and have picked up several new ones at very reasonable prices. I don't know what WT-76 series carbs are still available new, if any.

There are quite a few other replacements for the WT-76 series such as the WT-201 as used on the DA 50 but most don't adapt as well to the Brison engine throttle linkage as well as the WT-76 series.

All Day Dan

My Feedback: (5)

Thanks for the inputs. Truck, you're right about the Brison linkage. Not all of the WTs have the right setup.
It looks like I’m stuck with this new version of the carburetor unless I can find some new old stock. This spring activated choke is probably a good way to go for guys who use a servo to open and close the choke. With the spring removed and no detent it will be easier to set up. I use my hand to close the choke and the detent is necessary. Now I’ll be dependent on the position of the throttle plate shaft to keep it in place. When the throttle is opened past idle, the choke pops open.

av8tor1977

My Feedback: (6)

Is this a replacement carb for you and you still have the old one? If so, just change out the choke shafts along with the little ball and spring for the detent. Be careful to hold your finger over the hole for the ball and spring when removing the choke shaft, or as the shaft comes out the little ball will fly off to "never never land." (Possibly the spring too.) Also, as I mentioned before you will need to grind off the swaged part of the screws for the choke butterflies off before removing them.

AV8TOR

All Day Dan

My Feedback: (5)

W8, yes this is a replacement for the original WT-76-1. It turns out that human error caused the failure of the original one and I am going to give it another try after I get the right diaphragm in. In any case it looks like I’m going to have to live with the characteristics of the newer version because that is the way Walbro is going to make them whether I like it or not. You bring up an interesting point about that swaged screw that keeps the two plates in place. I have had to loosen them on rare occasions to reseat the plates properly and vaguely remember removing one or two. If that action ruins the tapped holes in the shaft, then how did Walbro screw them in during the assembly process? If I grind off the swaged end, how would a new screw work that is not swaged? Dan.

av8tor1977

My Feedback: (6)

The screws are installed, and then swaged by Walbro so that they can never work their way out and go into the engine. The "swaging" deforms and enlarges the end of the screw so that even if the screw should come loose, it could not then vibrate on out and enter the engine.

You just take an appropriate grinding tool in a Dremel tool, a small round stone works well, and grind the end of that screw flush with the surface of the choke shaft. That removes the swage and you can then unscrew the screw without damaging the choke shaft. Then, after you have changed the various parts and are ready to put it back together, just clean the screw hole in the choke shaft with alcohol or acetone, as well as the screw itself. Then use Loctite on the screw when re-assembling the choke mechanism. It won't come out, especially if you had the parts clean and allowed the Loctite overnight to dry. I have done this on dozens of carbs with no problems.....

AV8TOR

w8ye

My Feedback: (16)

The original screw was swaged after assembly.

If you remove the swagging & screw, then use LocTite at reassembly.

If the engine ingests this screw, it will ruin the engine completely.

thailazer

I have a Walbro copy made in Thailand and I simply unhooked the throttle and choke springs so the servo does not have to work against them. I didn't remove the springs but just released one end.

By the way, here is some information on the Walbro's: http://www.walbro.com/media/21907/WTseries.pdf

All Day Dan

My Feedback: (5)

AV8Tor, your post had me looking at the carburetor again. The choke shaft is yellowish so it’s probably brass. With the choke closed, the head of the screw faces outside. With the choke open, the body of the screw is below the surface of the carb body by about 3/16 of an inch. Assuming that the choke shaft was inserted into the carb body first, it would take an unusual tool or machine to reach in there and compress that screw. How did they do it? Dan.

av8tor1977

My Feedback: (6)

Well, two things. One, they have jigs and things we can't even conceive of to do what they need to do in manufacturing. Additionally, I am not familiar with that particular carb, but perhaps that carb is made such that they can open the choke enough to swage the screw before they install/enable the stop portion of the assembly. They might even do it before the throttle butterfly is installed, thus giving them a straight shot at swaging the screw.

At any rate, it really doesn't matter how they did it; we must grind that swaged part of off the screw to remove it. If not, when the screw screws itself out of the choke shaft, it will destroy the screw hole and threads in the shaft. Then you will never get a screw to hold again and will need a new choke shaft.

Once again, I have done it many, many times. Just grind that swaged part of the screw off, remove the screw, do whatever you need to do with the choke assembly, and re-assemble with Loctite. It takes more time to describe than it does to do the operation, and I have done it more times than I can count without problems....

AV8TOR

All Day Dan

My Feedback: (5)

av8tor, thanks for all your inputs. I remember loosening two or three of the plate screws, choke and throttle, to relocate displaced plates but I could not tell you for sure if I ever removed one. To tell you the truth I'm more inclined to replace the carb in the future. Dan.

Bass1

Just saw this thread and not sure if we are talking about the same thing but on my new 76-1 carb with spring loaded choke all I do is manually close choke plate with a small wire extension out of cowl, apply full throttle on transmitter( while holding choke in closed position) to lock choke in place, pull back throttle to idle position, flip prop until engine fires, blip the throttle stick a bit and the choke automatically releases, continue your normal procedure for final engine start. Works great

captinjohn

I had a throttle shaft break on a Walbro carb made in Japan for a Mintor 22cc engine. I ended up using a throttle shaft from another carb. I would have replaced the carb but they are not available from Walbro . Also note you cannot just install any standard carb, because the bolt holes are smaller. They placed bushings in the bolt holes. See photo below.

All Day Dan

My Feedback: (5)

Bass, that is a clever way to overcome the problem. I never thought about it. Here is the approach I am going to take. I got the shaft, ball and spring from one of the online retailers. Dan.
http://thecubden.org/carb/carbchoke.html