Emulsion tubes: are the holes important?

[Incubus]

Well,that's not exactly my question. I know the holes are important to vaporizing the fuel. My question actually is whether the number of holes in all the emulsion tubes should match.

I noticed as I was cleaning the emulsion tubes that the number of side holes differed from tube to tube. Two of them had three holes one way and two the other. The other two had four holes one way and three the other. How important is it that the tubes match? Are they supposed to be different for different carbs?

I don't know if this is expected or if my PO just threw in the parts he had available when last he did the carbs. I rather suspect as much, as the main jets also do not match. At least one is stock 137.5, one other is 142.5 and I can't read the size on the other two. I see new mains in my future.

Patrick

[Geezer]

I've never seen them not matched in a set of carbs and I thought I'd seen everything. I'd suggest looking for a matching set.

Geezer

[jjwaller]

Mikes XS has the all the jets and emulsions.
BS-34's for the tubes, and large mains for the jets.

[Incubus]

As I think about mains and MikesXS, I will be running a Kerker four-one and a stock, probably UNI, air filter. I've looked at the carb jetting info and I was thinking perhaps I should just go stock. I can always adjust a bit with the floats if that's a little lean. Does that reasoning seem sound? Should I go 140 instead of stock 137.5?

I can get 137.5 and 142.5 locally, and I usually prefer to buy locally when I can so my neighbors can keep their jobs. I don't foresee doing anything to justify jumping two sizes, though, so 137.5s are what I can buy here.

Patrick

[psycoreefer]

what year is your bike? Mines a 79 special and my tubes didn't match. If you check the factory parts numbers they center two used different tubes. I remember some were stamped 300 X2 and some were 266 X2, can't remember which ones come from the center carbs.

Mikes XS does have tubes and jets that will fit our carbs but the tubes are not the stock sizes for our bikes, if you go to mikes tubes you will have some extra tunning to do in order to get the mixture right.

[Incubus]

My bike is a '79 Standard. Which ones went in the middle, Psyco? The ones with seven holes or the ones with five? I didn't noticed the difference until after I pulled them out of the carb cleaner.

[psycoreefer]

you'll have to look for the numbers on the tubes, the ones marked 266-X2 are for the outside, 1&4. The others I think were 301-X2's and are for the middle cylinders. I don't remember the hole count, if you search for my previous posts you might find one that says, I went through a lot of trouble to get new tubes for my carbs and made several posts about it.

[petejw]

Hey Succubus,
Some of the model carbs came with richer settings in
the middle carbs to keep the inner cylinders cooler.
The more holes in the side of the tube allows more air in
resulting in a leaner mixture.
If you want to reuse the ones you have, put the 2 tubes with the least
holes in the middle the other 2 to the outer.
These carbs usually had different main jets, what are the main jets fitted with these carbs?

[gk45241]

OK I just had my carbs apart and pulled my Tubes to make sure they were unobstructed. THe ones with the larger hole count were on the 1 and 4 carb on my rack. I pulled them one at a time and placed them back in before moving on. I have 137.5 across the board.. Is the previous owner putting it to me? Are mine out of order. Now I'm confused..(I know, Big shock )


GARY

[red bandit]

gk45241, that's the way it is supossed to be.

[Incubus]

I didn't noticed which jets went with which tubes. I assumed when I pulled them that they would all be the same. Guess I'll pull the emulsion tubes again and make sure the ones with more holes go to the outside. I plan to get 137.5 or 142.5 mains across the board.

Patrick

[thewiz]

Nope, GK ...

that's the way the ones on my F are too ... I'm about 99% certain the carbs were never apart before I did 'em. Leaner tubes (more holes) to the outside, richer ones in the middle.

[Incubus]

I know these carbs were apart before. Scars on the jets told me that. Now that it seems to be reasonably established that the tubes are correct (took my carbs back apart, turns out I had them exactly backward) can anyone think of a reason why my PO would have mismatched jets? One is 137.5, one is 142.5 and the other two are too worn to read the sizes anymore. Unless PO was just using whatever he had laying around (or misread the sizes when he put them in), it is reasonable to assume the other two match what I can read.

The bike had a Kerker 4-1 and a foam filter. Would you want the middle so much richer you would go two jet sizes up? Or could the larger jet sizes be on the outside to compensate for the leaner mixture?

This feels like a learning experience....

Patrick

[bikerphil]

The correct setup is richer emulsion tubes in the 2 center carbs and the same size jets all the way across the board. Some 80-81 carbs used leaner mains in the outer carbs, but your earlier style carbs should be the same all the way across.