Repair on Carburetor Float Pivot Post

[canuck1969]

Going to repost this from my Project Build thread with a separate title. Came across a broken float post and after a unsuccessful attempt at a solder, found success in the process below. The sleeve is what really holds it in place once the bowl is put back on but the epoxy was just some added insurance. For what its worth the epoxy that I used sticks to this metal extremely well. Hitting the finished arrangement with a hammer did no damage. May be useful to someone.

Re-Post from thread:

http://www.xs650.com/threads/project-canuck-84-xs650-project-build.52613/

Well I could not leave well enough alone (another bad trait of mine). I was not going to let this thing beat me....and I didn't.

Ended up fabing up a brass sleeve from a piece of brass piping nipple at Home Depot. Together with some high strength chemcial resistant 5 minute epoxy, problem solved.

To prep the broken pieces, I chamfered the edges of both halves being careful not to grind the middle of the broken piece as that is what set the height and orientation of the final fit. I then cut a slot with my grinder in both halves to grip the epoxy in the sleeve. This will ensure it does not move.

Cut a length of pipe and then used my Dremel to cut out a slot to accept the gusset in the casting. It was a 1/8" brass pipe nipple that I used. The OD was 0.4" and ID was 0.275. Cut the length enough to accept the broken piece with about an 1/8" reveal on top so the epoxy can exit and fill the top .

The trick was that the pipe needs to be very thin on one side as you can see in the picture. This is so the bowl can fit back on. I just kept grinding, marking and fitting until the bowl went on without any issues.

I then cleaned everything with contact cleaner to get rid of any oil or flux from my previous attempt. Did a final dry fit to make sure everything would line up properly before the epoxy. Turns out an 8p finishing nail is the perfect fit. Used it because it was longer and allowed me to get a better hold of things until they set.

Filled the notch in the bottom half with epoxy and a bit around the post and then set the sleeve. Then filled the sleeve half way with epoxy and inserted the broken section using the nail to keep every thing lines up properly. Added a bit of epoxy to the gusset area to hold the sleeve. Turns out the epoxy I used sticks very well to this metal. ( LePage Instant Mix Speed Set Epoxy)

Strong as hell. Literally tried to move the post and it did not budge. The epoxy is really just some added insurance. With just the sleeve the post stays in place since the bowl somewhat holds it in place.

Float moves freely and no apparent issues. Will re-assemble and give it a go.

 

[5twins]

Nice job. The only suggestion I have is to insert the pivot pin from the other side so the head ends up against the still good post. The shaft just under the head is a slightly larger diameter than the rest of the pin and wedges into the post to hold it in. When you tap it out, all the stress and strain during removal is focused on the post by the head. Better it be that still intact one.

 

[canuck1969]

Nice job. The only suggestion I have is to insert the pivot pin from the other side so the head ends up against the still good post. The shaft just under the head is a slightly larger diameter than the rest of the pin and wedges into the post to hold it in. When you tap it out, all the stress and strain during removal is focused on the post by the head. Better it be that still intact one.

I was actually going down that way, but after hitting the repaired post with a hammer a couple of times I swear it is stronger than the original. Will look at that when I take everything apart again. Thanks for the heads up.

On a similar note, the pin was slightly bent at the head end. I was wondering if that was intentional to give it a tighter fit. I straightened it out and it actually slides in further with less grip. All that being said, the 8p nail seemed to be a better overall fit. Tight enough not to fall out or bind and loose enough to easily extract. Who know, maybe the nail will be the next best upgrade to prevent post damage.

 

[5twins]

No, a bent pivot pin is not intentional. Also, you needn't tap it in all the way until the "nail head" bottoms out against the post. You only need it in far enough so the other end sticks fully through the other post. That should leave a small space between the "nail head" and the post. This can come in handy when extracting the pin. Sometimes you can grip it under the head with a small pair of side cutters and pull it out if it's not stuck in there too hard.

 

[canuck1969]

No, a bent pivot pin is not intentional. Also, you needn't tap it in all the way until the "nail head" bottoms out against the post. You only need it in far enough so the other end sticks fully through the other post. That should leave a small space between the "nail head" and the post. This can come in handy when extracting the pin. Sometimes you can grip it under the head with a small pair of side cutters and pull it out if it's not stuck in there too hard.

Agreed...that is how I started to remove it (after the repair), with a pair of nippers. That way you can twist it at the same time.

 

[Downeaster]

Interesting.

I do some modeling in brass and have a number of sizes and shapes of brass tubing. I suspect that would work just as well and save a ton of filing and fitting.

Just for future reference if anyone else goes this route.

Available here

 

[MaxPete]

Yup - just drop into your local model aircraft hobby shop. They will have a huge rack of brass - tubing, flat stock, square stock, rod etc. etc. in lengths up to 36" long.

 

[canuck1969]

Interesting.

I do some modeling in brass and have a number of sizes and shapes of brass tubing. I suspect that would work just as well and save a ton of filing and fitting.

Just for future reference if anyone else goes this route.

Available here

Good to know for next time. That would be the best course of action. You want the post to fit in the tube tight enough that it will not rock but loose enough that some epoxy can still flow. The pipe I used was .281” ID and was a perfect fit. Thinner wall would have saved a lot time in grinding it down.

 

[Downeaster]

Yup - just drop into your local model aircraft hobby shop. They will have a huge rack of brass - tubing, flat stock, square stock, rod etc. etc. in lengths up to 36" long.

Sadly, my "local" shop (25 miles away) closed it's doors and the next nearest place that stocks ANY brass is 65 miles away and their selection is extremely limited. They're mostly focused on the scrapbooking and knicky-knacky crowd. 3000 square feet of dried flowers, one short aisle of modeling stuff.

Ordering online gets expensive quick as they have minimum quantities. If I ordered the MQ of each shape I use, I'd have a couple of lifetimes worth.

 

[Superjet]

Will the epoxy withstand todays fuel mix?

 

[canuck1969]

Will the epoxy withstand todays fuel mix?

Only time will tell. I am not to worried if the epoxy weakens as the sleeve keeps the post in line even without the epoxy. Once the bowl is put back on it locks the post in place. The sleeve is only really needed to keep the post from moving latterly. The pin float pin keeps it from twisting so the epoxy is really just overkill.

 

[59Tebo]

You want the post to fit in the tube tight enough that it will not rock but loose enough that some epoxy can still flow.

You might also use a mini pin file to file flutes (vertically). Like a dowel used in carpentry, it would serve the same function of holding/flowing the adhesive....

 

[canuck1969]

You might also use a mini pin file to file flutes (vertically). Like a dowel used in carpentry, it would serve the same function of holding/flowing the adhesive....

Possibly. That was the purpose of the slots I cut in both halves. They act as a wedge when they fill with epoxy and adhere to the sleeve. The gap was minimal between the post and sleeve but enough to get a coating of epoxy and move it to the top and bottom. Adding the epoxy in two steps ensured it would coat everything.

Again don’t overthink the epoxy. The main strength of the repair is the sleeve itself. You could also crimp the sleeve around the location of the cut slots in the post with some nippers if one was nervous about using the epoxy. Guaranteed it would never move.

 

[grizld1]

Good work, canuck! Wouldn't want to overthink the issue, but original formula JB Weld (not JB Quick) tolerates ethanol fuel very nicely.

 

[canuck1969]

Good work, canuck! Wouldn't want to overthink the issue, but original formula JB Weld (not JB Quick) tolerates ethanol fuel very nicely.

Agreed.....although I have never had good success with JB Weld sticking very well to these materials. I guess with the notch in the post it would still hold it in place as long as it sticks well to the brass. This epoxy stuck remarkably well to the mystery metal.

Keep in mind that the post ideally would never be immersed in the fuel and only be vapors. It would take a while for the vapors to work there way to where the epoxy wedges are as the entire sleeve annulas is flooded with epoxy. Definitely some room for improvement the next time it is attempted.

I still have some epoxy. Going to try an immersion test to see how it holds up submerged in fuel. They say it is chemical and solvent resistant, but I know fuel is another story.

 

[grizld1]

When I banked a pair of Mikuni TM36/68s a few years back and modified them to run off a single accelerator pump, I filled the pump cylinder in one float bowl with JB Weld. It adhered, but those carbs are aluminum, not the zinc alloy you had to work with. Immersion in 10% ethanol gas hasn't fazed that stuff.