Solex Carb Throttle Shaft Bushings

I did a homebrew fix (OK it's not totally a SPOT) that has been working quite well now for 7 years. You can try this at your own risk - I had 2 backup lower bodies in case I botched one up. Or you can go to professional shop. I have heard of the teflon bushes but teflon cold flows and you end up with a wobbling shaft after time. Teflon's surface is soft that enable dust/dirt to imbed and wear your shaft. There are some other materials that would be better like sintered brass and some of the new DuPont engineering plastics used in bushes. Not going to give all my SPOTS away!;-)

I'm sorry I don't have all the dimensional data with me for this but this should explain it enough to make sense. I took the original, i.e. replacement steel shaft that comes in the overhaul kit, went down to my local hobby shop and found the precision brass tubes used for model making that would fit snugly but not binding over the shaft. I got the closest drill (within 0.002 inches oversize and not a bit undersized) to the OD of the tube. If you have access to an adjustable reemer 'tis better. Measured the depth (or length) of the bearing surfaces needed for both sides of the carb. Cut the 2 pieces of tubing about 0.25" (1/4") longer than needed. Use a Dremel motor tool with an abrasive cutoff wheel or a fine toothed model maker's saw to cut to length. Make sure that you deburr the inside of the end that will be pressed into the lower body.
Check using the new shaft! In my case the wear on the lower body was not quite enough to drop these new bushing in so I used a drill press (make sure the table is square to the spindle)to do the following:

1. Carefully clamp the lower body in the drill press vise (machinist vise) and plumb things up. You can use the throttle shaft to assist. You can "eyeball" vertical or use a dial indicator (or a good triangle or square for truing up all axis. That should get you close enough or within a mil (0.001") or two.
2. Using the drill point (better yet is a counter sink) align the center of the hole under the spindle. That is bring the spindle down on the hole and turn by hand until it is lined up. Clamp the vise to the table once located.
3. DON"T FORGET YOU SAFETY GLASSES HERE! I ran the drill press at a medium speed (about 800-1000 rpm) and proceeded to bring the spundle down slowly, using some lubricant on the bit or reemer to keep it from binding and chattering. Pot metal is soft and it can easily bindup and trash you lower body. That's why you clamp the vise down to the table besides it's safer that way.

You will need to get some Loctite penetrating thread locking compound and ACTIVTOR. NAPA has that and I think it was Loctite 490. You need the activtor as these metal (brass and pot metal need a little help in setting up the bond). Keep all this stuff from the inside of the bushes and shaft. Follow the directions from Loctite and apply activator to the bore of the lower body and the outside of the new bushes - "q-tips" work great. BTW clean the surfaces throughly (no oil or gunk) and you could Scotchbrite (green pad) the outer surface of the bush to remove the oxidation if they're not bright.

After the holes have been bored, using the OLD shaft with a nut and *tight* fitting washer, push or LIGHTLY tap the new bushes into the body. Do not drive the bushes flush to the inside bore! Leave about 0.020" from the inside of the bore - you don't want to have any interference with the throttle plate! Now using your new shaft unless you old shaft is in good shape like mine was, insert it into the new bushings to line them up. Now VERY CAREFULLY apply a small amount of the thread locking compound to the outer surface of the bushes - that's why the minimum of 1/4" longer was needed - to help guide the adhesive to the right place. I found that a diabetics syringe works well for this use you Dremel or sharpening stone to get rid of the sharp injection point - be careful!!

Let this sit overnight, You can remove the shaft after several hours but I would carefully test periodically to make sure you didn't bond the shaft! Then carefully file the bush that is still sticking out flush to the surface. Use a sharp, fine mill bastard file, not a good place for the Dremel! Use a countersink drill or hand reemer to deburr the end just filed. Go slow as one can easily distort the tube making a mess of things. You might have to work at getting the shaft to freely (not wobbling) rotate. I used my an old, worn shaft with some fine lapping compound to get it just perfect. I reassembled using a synthetic teflon loaded grease. The shaft is still tight (<0.001 inch radial free play - wobble) after 7 years.

BTW I am looking for a 28mm Solex choke tube (carb venturi) which was used on some Solex carbs. The standard on the IIA's w/7:1 heads seemed to be 26mm - that dimension is the middle number of the three that you see as you look down the carb. I had a 28mm on an older III I had converted to Solex and it really helped performance and mileage. My next GOT (good owner trick) is to re-machine my existing tube to open it up and maintain the venturi curve contours. Also am looking for a 117.5 and 115 main jets for the Solex (that's the 7-11K ft altitude jets) and a couple of the long screws that hold the starter body (with heater element) to the lower body. Drop me a note if you have any of these you might be willing to part with from your parts inventory (ie the "hellbox").