Carb repairs

[cajun31]

Looking for input, experiences... etc.. To make a long story short I purchased a couple sets of carbs ... several years ago as spares. I have been using my ... confined time... messing with these old carb banks. While disassembling them I have discovered a few problems and want suggestions on how to repair. I have one that has a stripped out pilot jet tunnel and another one with the same problem only it is the pilot screw tunnel that is stripped. I have done some research and came up witj the following. The pilot screw is 6 x .5 mm and the pilot jet is 5 x .8 mm. Can anyone verify these sizes for me? I also want to know what if anything can be done to repair them. The threads are gone so re-tapping is not a solution. I have been looking at helicoill. I can't find any in the 6 x .5 mm size. 5 x .8 mm can be found. I have located a source for a 6 X .5 mm tap but so far the only helicoil inserts I find are 6 x 1 mm size. They are made of stainless and I was wondering if I went with that size could it be re-drilled and re tapped to a smaller size to fit the pilot screw. Of course I would set it with red loctite first. Anyhow... thought I might get a healthy discussion started on how best to attack these problems. Suggestions?

[cajun31]

oh and by the way I am still hoping that someone just has a spare special style number 1 and 4 carb they can sell me.

[red bandit]

What year carbs?

[Bax]

Hey Cajun, Not good news here. On thread repair for the pilot screw tunnel any retap attempt would need to be very precise so the needle tip properly aligns to the seat. Helicoils are not a good solution for these small thread applications in Aluminum. For the pilot jet, precision alignment is not as critical but still small threads pose a problematic condition with engagement. Base metal repairs (weld fill) and a recut are the ultimate best method. Making an insert with small interference to press in tight after drilling out the damaged threads in the tunnel may get you some mileage. I checked the time sert site and they do not offer Aluminum inserts in the sizes needed. It's probably easier and more reliable to locate replacement bodies for these two carbs.

http://www.timesert.com/html/mtrcsert-aluminum.html

https://www.alumaloy.com/copy-of-int...-of-spec-aluma


May be able to fill and successfully retap after a coating of Alumaloy but I'd try a few practice runs on something disposable first.........


---Bax

[Bonz]

How about finding a set of four carburetors? I bet there are some carbs out there that someone would pony up to help you. That’s only a suggestion and I can’t be part of the solution as I don’t have any carburetors but maybe a thought.

[cajun31]

Red Bandit... I am looking for 80 or 81 special type carbs. I have been told that the later 79's work too as well as the 80 and 81 standards.

Bax... thanks for the input. You brought up some points that I had not even considered. Alignment would be a problem. Basically these carbs that I am working on could definitely be the carbs to experiment with. They are no good without some kind of repair. Whoever messed them up did a good job in that regard. They then just stuck the jets back in and sold them. Of course thinking back ... I bought these some time ago... 15 plus years ago and I know I did not pay over 50 dollars for the set. Carbs are getting more and more difficult to locate with the cafe craze going on now. I will look into some of the things you suggested.

Bonz.... I have posted for carbs and Kurt helped out. Like I told him I would rather not bust up and entire bank of carbs that are in otherwise workable condition to repair my bank. Ideally what I would like to locate is someone that has a broken bank with a good number 1 and 4 or someone with loose carbs they are willing to part with.

I am still open to suggestions from others. Continue the discussion.

[Bonz]

I understand what you’re saying, however I’m saying I don’t understand (or maybe I missed it) not finding a bank of good carburetors and going with those instead of piecing together something if you can find the individual carbs to do it. My thought is most guys are going to have complete banks of carburetors and to find a spare number one and number four laying around might not be as likely. By getting a complete bank of carburetors you have a number two and number three as spares down the road.

I hope things work out for you!

[cajun31]

Howard... I hear what you are saying. I may luck up and find the carb bodies I am looking for. I keep a constant eye out for them. I almost bought a no. 4 from Germany but the guy simply wanted way too much for one carb body. Didn't even have jets or anything and he wanted close to 80.00 plus shipping. I haven't reached that point yet.

Bax... I looked at the alumaloy site and those products look very promising. Looks like a drill press is in my future. This product might even be viable for broken posts.

Has anyone else out there experimented with the type of repairs I am looking at? Failures ? Successes? Keep the conversation going. I am sure there are others out there that have the same problems.

[Bax]

cajun31 Cajun, I have a few pounds of the Alumaloy rod in my garage. PM me your addy and I'll send you a few rods to play around with. For the broken float posts I've done similar repairs on aluminum with this stuff and it probably would work well. Probably want to use a torch with a small and focused blow pipe.

[Ranger_xs1100]

oh and by the way I am still hoping that someone just has a spare special style number 1 and 4 carb they can sell me.

Cajun, I checked in my box of misc carbs and found that I don't have a #1 but I do have a #4 that I believe is off of a special. (If the upload works, it's the bottom carb in the picture, ) ... the slide and the butterfly moves freely and the main jet turned freely. and the body appears to be in good shape, however the other jets may be stuck. I made a weak attempt to unscrew the pilot jet and felt the screwdriver start to slip and the jet didn't budge, the mixture screw also didn't budge. so there will be some work required there. If interested, PM me when you get a chance. Bob

[cajun31]

Cajun, I checked in my box of misc carbs and found that I don't have a #1 but I do have a #4 that I believe is off of a special. (If the upload works, it's the bottom carb in the picture, ) ... the slide and the butterfly moves freely and the main jet turned freely. and the body appears to be in good shape, however the other jets may be stuck. I made a weak attempt to unscrew the pilot jet and felt the screwdriver start to slip and the jet didn't budge, the mixture screw also didn't budge. so there will be some work required there. If interested, PM me when you get a chance. Bob

I messaged you on the carb. By the way I have followed your bike projects on wordpress. Very nice work and the bikes turned out amazing. Keep it up ... restoring these bikes is a great hobby. Of course I am biased and love the original. Some of the cafes are interesting but I am way too old to give up comfort for style.

[Ranger_xs1100]

Got it Cajun, I'll get that carb out to you by the end of the week.

[cajun31]

Thanks Bob...

[cajun31]

update on my carb repairs... I did not have any success. I used a propane torch to heat the carbs when trying to apply the Alumaloy and either I am doing it wrong or the metals are incompatible. The instructions on the Alumaloy state to clean the area you want to treat with a wire brush which I did and bring the metal up to the right temperature so that the rod will melt to it when you touch the heated area. I thought I followed the directions ..one small problem... or rather a couple of problems. First... after holding the torch on the area for some time.. thinking the area was hot enough... I touched it with the rod and nothing. So even though the instructions tell you not to heat the rod directly with the flame it was the only way I could get the rod to melt at all. The instructions state that if you did that it makes the metal crumbly... their terms. I guess crumbly must also mean no adhesion. I could put a drop of the rod on the area and after cooling down and trying to file or drill it would just come right off. I had one carb that had a broken float post and I still had the piece that was broken off and it fit right back on. Broke clean.... not my doing ... bought the carb set that way. Anyway I decided to give that a try by holding the piece in place while I heated it up so that I could basically tac weld it in place with the rod. Same propane torch ... the small piece I was trying to tac on to the post actually melted before the rod would. I am sure their are uses for these rods or I need to practice more but so far no luck.

[DiverRay]

You probably need a MAP gas torch, they are a much hotter flame. I'm not sure the rod will work on the carbs, as I believe they have a lot of zinc in the alloy.
The post can be repaired with a small set screw. Drill and tap one side, put the screw in part way, center the other part and tap lightly to mark. Drill and tap side two then screw together. You can adjust the set screw to get them to align. It's a bit fiddly, but permanent.
Look at your parts store or online for gas proof epoxy. You can also use that for the post repair as well as re-building the missing metal on the carb body.