'83 GS550L Siamese Dual Carbs Cleaning and exhaust question. Mikuni BS30

[benaqui24]

(Disclaimer - I couldn't find any number stamps or markings on these carbs)

So I started this thread a little while back...
https://www.thegsresources.com/_for...S550L-in-Wisconsin-needs-some-work&highlight=

Since then I've taken care of a few problems. Did the valve adjustment, they were all under .004". I recently pulled the carbs to check the "work" the shop I bought it from did. They looked clean, but of course there is a couple problems. One of the idle jets(cyl 3) was to stripped to get out. And the others looked pretty ham fisted too. I would like to just order a full set of jets.

It was pretty hard to read the jets but here is what I think I've got...

Cyl 1 2 3 4
Main 95 105 95 115
Idle (stuck) 35 58 58

I also assumed the needles on the intake side were supposed to be tune-able, but those seem to be factory set too.
My concern is that all 4 mixture screws(top front of carb) were backed out by 3 turns. The bike sounds louder than it should be stock. But I'm not very familiar with GS's.
Can someone tell me if this exhaust looks drilled out, or stock?

(BTW I'm in Madison if anybody nearby has advice. I have beer...)

Carb Pics

 

[benaqui24]

I did find some wear in both needle valves. A small ring about 2/3rds down. I polished them both and the jet needle that had some silver showing. All 4 jet needles looked to be angled ok.

 

[Steve]

Mufflers: "Drilled out?" Surely you jest. Do you really think that anyone at a factory is going to release anything that looks like that?
Look for the evenly-spaced holes, they are the originals. Even then, they might be drilled, too.

The factory exhaust might have had holes, might have had dimples, but there were only SEVEN locations, a larger one in the middle and six medium-size ones around it. On different models, I have seen just the center hole open (the six others were closed) or the six holes open (and the central one closed). Not sure if I have seen all seven open from the factory. All those other irregularly-spaced holes are extra, and, of course, noisy.


Carbs: I have rebuilt a couple of sets and had to get some spares in the process. Not sure if they might be useable, but I did get the parts I needed off them.

Your main jets are supposed to be different sizes, but not arranged like that. 1&4 should be 95, 2&3 should be 102.5. The holes in the mufflers are not enough to affect jetting.

As for the other parts, some aren't so bad, but others are highly questionable.

Here is one of the sets when I got done:

.

 

[benaqui24]

"Don't call me Shirley, and the bikes name is Sally, FYI"

So would you think it would be better to put in another set of jets at stock size then? I just want to replace them since the heads are all torn up. I'm just working on one problem at a time here. Next will be brakes, then chain/sprockets.

Did you find SN stamps on your carbs? I want to make sure these aren't just knock offs. I already replaced the broken choke guide nut. I've put new brushes in the starter and ran 6ga cable for it and the ground. new charged battery too.

The manual says the little screws on the carb intake side adjust the needles. But that doesn't seem to be the case on these ones. Is it a set jet/needle (and idle) or are these just stuck in my carbs?

 

[Cipher]

the 105 and 115 are likely 105s you are sure the 115 is not a misread?

if so outboard takes the small one inboard large ones.

Different jurisdictions had different jettings.

mine are 97.5 and 105 stock

that exhaust looks like crap why do people do that?

 

[benaqui24]

I probably misread them, but the screw slots are pretty torn up too. Has anybody had luck getting an idle jet out? Like with a reverse threaded screw or something?

Is there any point in trying to epoxy the holes up? I don't plan on replacing the pipes. At least they don't sound horrible.

 

[benaqui24]

Does anybody have a trick for getting the battery and airbox out on the 83 L model? I keep fighting with the carb boots and don't want to damage them. The manual I have from Basscliff is for the E.

 

[Cipher]

oh you are in for fun
easy removal of the airbox without damage requires you to remove the rear wheel
iirc you also have to disconnect the cushion lever assembly where it bolts to the frame. Two really large dia. but short bolts allow this.

I cant recall exactly but this allows the swingarm and and the bit the battery box rests on to drop away giving tou space.

I think you get enough play this way to get the carbs out but i would take it all out
new boots airbox to carb are a nice thing as new is pliable rubber and old feels like slick hard plastic very hard to deal with

a bonus of the rear suspension drop is you can disassemble all the cushion lever bits and clean and regrease. This system has a nasty habit of getting fine dirt packed into the seals leading to an insanely loud squekaing that can be heard above engine and road noise even at a pretty high speed.

 

[benaqui24]

Well, that doesn't sound like much fun at all.
I thought it looked like if I unclipped the fuse box, and unbolted the R/R(screws spin in place on the plastic now), I might be able to lift out the battery box. Then I saw that they are connected? But it looks like there is an airbox bolt that goes into some kind of square clip on the battery side.
Is there really no guides on the 83 dual carbs? If I can get enough help on a better way to get the carbs and boots back in, I wouldn't mind doing a write up. I already have the pics.

Ohh, also do these carbs actually have clips on the needles? I didn't want to break mine to find out.

 

[Cipher]

yes clips on needles I think only one notch ill go check
oh and yes remove reg rect and two bolt batter box comes out if igniter is also removed

but

airbox needs that bit dropped im almost certain
been ages since I did it though