I finally got to run my G26 with the new WA 167 carb. I had changed out the cover with the bulb and plastic thing and installed the cover from the original carb. The one with the brass tube soldered on it. I ran the tubing into the fuse as before. I would only run if I kept choking it with my finger. I knew at that point that it wasn't getting any fuel but didn't know if was pumping or if the holes were blocked that makes the pump work. I removed the old cover and reinstalled the one that came on it. I pumped the bulb and it filled with gas which I assumed proved the pump was working after all. I hit it with my starter and it came to life and ran fine. I adjusted the needles and all seemed to be fine. It started to act odd in transition and then began to very slowly return to idle when the throttle was pulled back to idle. I realized the throttle on the carb as I had it rigged was dragging or jambing up. I was using a cable due to the difference in where the servo is located and where it exits the firewall which is very near the top. I had fashioned a bell crank and it worked smoothly for a for less than half a tank of gas before it gave me trouble. I removed the carb and even with the throttle removed, the butterfly drags some. I unhooked the little return spring but that doesn't help much either. I can't figure out what is causing the butterfly to drag. I watched it closely and noticed that as I work the butterfly open and closed it moves latterly some, even feels like it is spring loaded or something. As I slowly open the butterfly, it moves a little side to side inside the housing. As it stands now, there is way too much resistance and the cable bends. Due to the way I have to rig it up, the servo must PULL the cable to open and PUSH it to close. It's the closing thats causing my problem. When it tries to push the throttle closed it's bending the the transition is very poor to naught.

Question is, can I grind off the idle screw mount to give me more room, and grind off the plate on the end of the butterfly and mount another type of arm without screwing up the carb? The throttle is going to have to have near zero resistance in order to use a cable.

The G26 comes with a WT645 carb that is bigger than a WA167 One is 1/2" and the other 7/16"

It's not good practice to use a steel throttle cable. It will transfer RFI back to the radio

I use that carb on a couple of engines. I found that there is sufficient protuding throttle shaft on opposite side of carb to slip on a wheel collar with a "sodered on" arm. Granted it requires modification for the pulse port alignment. I like a long arm on the throttle shaft.

Grinding off the parts won't hurt anything...Sometimes the shaft gets a little bent..Take the disc off and pull the shaft out to check for straightness...Put the shaft in until the second part of the shaft starts to enter the hole in the carb body, if it's not free you can CAREFULLY bend it a little until there is no friction at all with the shaft all the way in the carb body...Put the disc back on with some Loctite on the screw, making sure the beveled edges of the disc close the opening the right way.....Don't let excess Loctite run down the shaft into the hole..
The bulb has nothing to do with the pump part of the carb, it just fills the carb from the tank for starting...
There should be a snap ring or some type of end on the shaft opposite the spring..Some have a clip, some have a flat washer held on by a screw..ALL have something on there...The spring keeps the shaft against the stop on the other end, keeping the disc in the middle...
You need to hold the shaft against the stop on the end when tightening the disc...

I heve occasionally had carbs where the butterfly shaft bore got "hammered" by the butterfly valve.
This caused the shaft to grab. careful reaming if the bore cured the condition.
It is important to keep the valve from moving axially. Ralf gave a very good explanation, so I won't repeat that here.

Thanks everyone for the suggestions. And previors thanks, "axially" was the word I was looking for in trying to describe the movement of the butterfly. I believe that I'm going to have to go back to the drawing board on my entire throttle setup. I want the carb mounted to the engine as it is now so that I can access the needles without worrying about getting in the prop. It made adjustment a breeze. I'm just going to have to come up with a way to route the throttle control rod through the lower corner of the firewall in more of a straight line so I can use the plastic rod. It's going to take some real Rube Goldberg engineering.

In the short time it ran, something must have happened to the carb, maybe as Previors said. For it to have ran and the throttle work so smooth, and all of a sudden just go to h#ll, something must have happened to the carb.

I'll first remove the little plate and spring and see if it drags. If so, I'll remove the butterfly plate and the shaft to see why it's dragging.

Ralph, I thought about removing the disc on the butterfly but it looks like the screw is bradded on the inside and I just don't feel to good about trying to remove it. I pulled out your insulator that you sent me a while back and it will work with the 167. My question is what is it tapped for the carb bolts? I tried the ones that fit the stock one but they seem very tight going in. Whats odd is the same bolt that holds the insulator on fits for holding the carb on the stock one. But your flat head socket bolts, while they fit the engine don't seem to fit the insulator. Does any of that make sense? Bottom line tell me what they're tapped and I'll get some of 'em.

The throttle has a tiny bit of drag in one spot and for the life of me I can't see why. I left the spring on it and am using the plate to mount the push rod on. I think it's all gonna work ok soon as I get the correct bolts to hold the carb on.

Tapped for 10-32, made that way on purpose...The 5mm .8 stock carb bolts are about .006 larger and make for a good tight fit...You have to shorten the stock phillips head carb bolts to keep from bottoming out in the cylinder...
Use the stock bolts, just check the length first....The flatheads I use are 5mm .8 x 20 mm long, perfect fit in the cylinder and won't crack the insulator block..
You can take the disc out, won't hurt the shaft..Put some Loctite on the screw when you put it back in...Don't let the Loctite run down the shaft, it gets pretty tight...I KNOW

Thanks Ralph I'll be extra caustious with the length of the bolts. I did notice the length difference. I couldn't figure out what was going on, the thread pitch seemed to match because the bolts would go in about 3/16" before getting tight. Crap,,,, as usual I take my camera over to snap some pics and the forget to take em.

The pitch on the mm bolts is just slightly less than the 10-32, so the bolts are self locking, tight enough to squeak a little going in..10-32 X 1.5" Are just long enought to be perfect with a lock washer...There are no threads in the cylinder under the block...

Ralph I shortened the bolts and remade the threaded rod between the carb and push rod. As I said I used your insulator which allowed me to turn the carb over and put the throttle plate on the bottom away from the magneto. I screwed the carb on and those screws did SQUEAK as they went in. I used flat and lock washers and it was difficult to get them in. I could have cut another 1/16" off the screw I guess. Here's a pic of the finished product. I want to thank you Ralph for the insulator. I hope, with the 167, my deadsticks will be over. It sure makes tuning alot easier.

I use 10-32 allens, 1 1/4 long..just right [8D]

I'll change them, then. I hate phillips head screws.

Same here, the Japanese make them from some old soft material...Takes a hammer operated phillips driver to get the 3 from the mounting plate on a G26...
sometimes you get lucky, even using the supplied phillips driver, but usually there's one that strips...

The right tool for the right job.... Those are NOT phillips. They are JIS cross slot screws. Get a set of JIS screw drivers and you wont round the slots out any more[] Of course you will still twist of the head cause cause the screw is made out of junk metal, but the slots won't be rounded out[X(]

I HAVE the plug wrench/screwdriver that comes with the engines, it's not much better than the screws....If you use it on good screws the cross slot wears out...I drill the heads off, unscrew the rest, and use grade 8 flathead Allens...