Another carb mystery!

[Crazcnuk]

Aren't they fun?

Just got a set of 1980G Carbs to play with. They were heavily gummed up, and full of crud, varnish etc.

Normal for thes carbs.

However, the fun starts with the set up.

These are 80's, but with the rubber plugs on the pilot holes, and x-hole to the main tower.

This set has 115 mains on all 4, #40 pilots, 170 air jets, 5D50 needles and X-6 tubes!

Is it just me or is this really bizarre?

This set has plastic floats, non-viton needles and 2 carbs have limiters on the floats (so they can't drop too far) and clips on the other 2.

There are no serial type numbers (ie 3u9) but they each have 49150 on them and D071(3) or D081(1)

[kirmit77]

This sounds like a job for the XSIVE GURU'S


sorry.... im no help....

[tarzan]

The mains should be good,pilots should be 42.5 but 40's might be close enough,but the air jets should be 185 IIRC.170 seems small.
I dont know what tubes and needles I have in my sg carbs.

[DGXSER]

Sounds like you got a set of the "crossover" 80s carbs. I've read here where some of the early 80s carbs had the pluged pilots and fed the pilots form the mains. Sounds like someone jetted them for the year and not the actual physical makeup of the carb to me.

The year does not make the carb. The fact it has the connector indicates the pilot is to be plugged from the bowl and the main increased to feed the pilot like the 78-79 carbs. All of the years had about the same pilots as stock IIRC 42.5 with some having maybe having 45s. I would suspect you want 137.5 mains to start with as "stock"

[Crazcnuk]

That's what I was thinking. Now I am running 120's on the non-xover carbs (up from 110), and it was running great.

Should I be going 145's or bigger yet?

I have been having good luck with 42 pilots.

These carbs also have a rubber washer under the bowl gasket (carb side) and rubber washers on the float bowl plugs, although they are the straight in style, like one set of my other 80 carbs.

[petejw]

Hey Craz,
You know how to pick em.
Sounds like someones been messing around with them, do you know any history of the carbs?
Whats the mixture screw set up, early or late model type?
The smaller air jet will increase the richness of the pilot jet "they' say
going up 1 size on the air jet is roughly equivelent to going down half a jet
size on the pilots.
If the pilot tower is blocked off, and you can see through the X tunnel, running larger (137) jets might be worth a try.
Got any pics?

[Crazcnuk]

Someone did some messing, alright. The bunged up the top of the mixture towers (80 style) I assume trying to get teh caps out.

2 of the float seats had the standard 'U' clamp, the other two have a u clamp with an extension that limits how far the floats can drop.

The needles look thicker than any I have seen, and both the needles and tubes are completely different.

There were no balls or springs on the choke rod, and I didn't see any place for them.

They had stuck the choke lever on with wood screws.

These carbs have very small slide springs, compared to my other two sets, yet the slides are the same size. The caps on top have smaller guides for the smaller springs.The slides also have a larger circlip with a plastic needle that sticks up into the slide. The needles have only 1 slot.

Carb 4 was completely gummed up, right to the top of the slide, inside. All 4 slides were stuck.

I have them mostly cleaned out, now. Just some stubborn varnish i am working on.

Everything is there, and they should be salvagable, unfortunately, they don't use the same jets, as my other ones, so I am going to have to buy some more main jets.

[red bandit]

If you have 80 emulsion tubes, 137.5 mains will be to big. Emulsion tubes are to mains as pilot air jets are to pilot jets.

[Crazcnuk]

Well, as mentioned above they aren't 80, or 79 or anything else I have ever seen.

The tubes are marked 818 X-6. The Needles are 5d50

[DGXSER]

If you have 80 emulsion tubes, 137.5 mains will be to big. Emulsion tubes are to mains as pilot air jets are to pilot jets.

Bandit, the mains are enlarged on the older style carbs that have the pilot jets covered and the cross tunnel as they mains now carry the pilot jets fuel as well. That is the main reason for the 137.5 stock main jet versus the 110-120 on the newer carbs as I understand it.

[Crazcnuk]

If you look at the sizing chart here;

http://www.motorcyclecarbs.com/Mikun...rt_W319C36.cfm

You can see that a -6 needle jet (tube) is .03 larger diameter than -0.
or .02 larger than the X-2 that these bikes usually use.

The 5D50 needle is very thick.

My question is: I am running the SG carbs, right now, with 120 mains, 42 pilots and 180 air jet. Should I be ordering 137.5 (stock) or 147.5 (same jump up) main jets?

Or should I be somewhere in between? I have stock exhaust with x-over and a K&N filter (single) at ~3400ft altitude.

Should I also change the air jet?

I am thinking I should go 142.5 mains, 42.5 pilots, 180 air.

[tarzan]

Maybe they aren't off of an XS.IT sounds like you have a set of bastards.lol

[Crazcnuk]

They came right off the 80G they were attached to. Beyond that I can't say. They are correct for an early 80 model so I have no reason to question what they are for. However, they do look like they have had some amateur work done to them.

For example, the two wood screws holding the choke lever on. At least they didn't force them in.

[Crazcnuk]

Tarzan hit it!

After some research, I believe these carbs are off of a Suzuki!

http://www.thegsresources.com/gs_carbrebuild.htm

The look very much like these, although without vent tees.

The 4***** part numbering goes with Susuki, too, although I haven't found 49150, yet.

This link shows BS32s on a GS850, which uses the 5d50 needle and X-5 tubes (close to X-6).

http://www.thegsresources.com/gs_carbrebuild.htm

It also has 115 mains, 40 pilot jet, 1.7 air jet etc.

[tarzan]

Well in that case maybe they will work with close to the setup it has.Are the carbs the same distance apart?If not maybe you can just use the rails off your fubarred carbs to get the spacing right.