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Hello everyone-
I've been wandering these forums for months now finding some great info! I'm posting now because I've not found what I am looking for. I have a 1979 GS550 that is great, ride-able post restore project. I found oil leaking from the between the head & block near the Exhaust manifold and decided the winter would be a good time to replace the headgasket. I'd assumed that the carburetors were fouled. I could only climb hills in first gear, the bike dies outright if you opened the throttle all the way from a stop, and It doesn't have enough power to cruise over bout 50 mph, not to mention the smell and signs of an engine running too rich.

Anyhow, to my problem: I purchased a carburetor rebuild kit for a 77-79 gs550 and found the the rebuild kit I purchased has parts that didn't match what I pulled out of the Carb.

In the photo below, the hardware above came from the rebuild kit, and the hardware below came out of the carburetor.
130213_0001.jpg

Many bits do match, but plenty do not. My parts supplier suggested that the carburetor could be from a 77-79 gs 650, 750 or 1000. Once the GS 550 hits 1980 and up, the carburetor looks quite different. I took some photos below can you name that carburetor? 130213_0005.jpg
130213_0006.jpg

Any help or identifying marks that can help me figure out what type of Carburetor I have would be great. Thanks!
T
 

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Pretty sure a generic kit 'almost' fits the 77~79.
Majority of parts will still be available from Suzuki
To identify carbs, you need model number which will be stamped or stenciled on body
If stenciled, it will be very faint (and if carbs have been 'dipped' probably missing.
Probably the only way to find out is genuine Suzuki manual, plus ALL the supplements
 

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Welcome to 'my world'...these kits are never quite what you hope they will be, but much better than nothing. I seldom use the replacement pilot screw needles unless they are a match for the old ones and I have never seen a kit that comes with the needle jet (the item that seems to take the most wear). In some stubborn cases I have had to machine the needle jets myself or go a hunting on eBay for NOS replacements. In any case, anything else that fits ought to work just fine. The GS550 is a nice bike...good luck with it!
 
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My searching turned up nothing solid either, but my guess is they're made by Mikuni... but not 100% on that one. The main wear item in carbs is the needle valve that lets fuel into the float bowl, gaskets and the o-rings. If those fit your carbs then you can use them.
 

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Discussion Starter #5
Mikuni Carburetors

Sabre - They are Mikuni Carburetors, I should have mentioned that in my first post, but you are correct, nice one! I guess I can refine my searching by comparing the jets, needles, etc that I have to what my parts guy has.

I can help my case by refining my question: On 77-79 GS models, how different are the carburetors when going from the 550 to 750 to 1000 cc motors?
I doubt anybody wants to take the time to explain Jet sizes between all the years, but if you know of a reference on the web where I might find some of that info, it would be great. As I mentioned before, my manual only covers 550 models from '77 on up.

I know that I have the Mikuni carburetors, built between '77 and '79. But If there is much of a difference between the Mikuni carbs on a 750 or 1000, that might help me know where to start looking for the right pieces.
Thanks for the help so far, I'm starting to think in the right direction, though, Im not pumped about spending the $ to have the jets machined =o/.
Trog
 

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the Jets machined?!?!? What. The. Fuck. slow your roll there. Those jets are commonly available so man up and do a little homework, machining anything (let alone paying someone else to do it) would be like having a billet wheel machined just to change a flat tire - so much overkill it doesn't make sense. Why do these fucking noobs always assume shit had to be "machined"? like people haven't been working out these simple problems for the last 35 years.

1st: the carbs are mukuni, but they used those style of carbs on the GS550, the GS650, and also Kz550, KZ650, etc....So the only real way to identify them is either by finding the marks like PJ says or measuring the inside diameter of the part that goes into the carb rubber. More than likely you have the stock carbs for your bike.

2nd: All aftermarket carb kits are junk. Don't pretend that they are not. The shit is made so fast and loose it is useless to you. Jets don't wear out - take your stock ones and clean them. Then clean them again, then clean them a third time. Then reuse them. Use only air and solvents to clean them - do not use a small file or a guitar string or what have you, too many noobs ruin jets by accidently opening up the orifices while trying to clean them. Don't even try to use the jets that came with the carb kit, THROW THEM AWAY. Your stock jets should all be stamped with a size, make a note of the size and make sure they are all the same for the jet type.

3rd: The only wear parts that are going to be an issue are the float needles and the rubber parts (like the o rings), which has been mentioned before but you must be illerate or not reading the replies. Chances are the needles in the kit aren't going to work. I have never recieved a kit that had 4 working float needles, usually the shape of the point is wrong or the diameter of the point is too small. Order four new float needles from suzuki. use those.

4th: throw your brand new carb kit away. They are a red herring for newbies to buy shit parts and in the end they cause more frustration than they fix bikes. you basically bought it for the rubber goods. Order the right OEM parts.

5th: Don't try to mod anything. Put it back to stock and attempt to get it to run. If you are being a dipshit and putting pods on it, save that for after you get the bike running right with the stock airbox. trying to jet a bike that isn't running right is just stupid.

6th: if you really can't figure this out, call sudco. They have been in business for decades and will walk you through everything you need for these carbs. They also stock oem parts from Mukuni so if you need jets they will have them, smae with float needles and o-rings.
 

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I've never bought a full rebuild kit. Usually just gaskets and rings...but even those you have to be careful with as there are some junk ones out there. Don't be cheap and lazy...clean what you can and find quality parts that you cant clean.
 

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I've never bought a full rebuild kit. Usually just gaskets and rings...but even those you have to be careful with as there are some junk ones out there. Don't be cheap and lazy...clean what you can and find quality parts that you cant clean.
Those are mikuni vm carbs... make sure to change out all the o-rings... and the o-rings in the carb intakes as well. I suggest going over to The GSResource Forums - Powered by vBulletin and this site... BikeCliff's Website

If you need to get/change out main/pilot jets, etc.... you can get them from z1 enterprises. Pretty knowledgeable folks over there.



Between those two sites, you should be able to get those carbs sorted.
 

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Here is BassCliff's VM carb rebuild document:
http://www.thegsresources.com/garage/docs/vm_carb_rebuild.pdf

It is very informative. As to the mis-matched parts, The only things I see that don't match are the pilot needles and the small springs, correct? There are two pilot screws on each carb, one on the side, and one on the bottom. It looks like they gave you the air pilot screw (on the side) and you removed the fuel pilot screw (from the bottom). The spring they provided goes on the air pilot screw they gave you. The spring you took out came from the fuel pilot screw you removed.

Here is a place to get o-rings for your carbs:
O-ring kit for the VM carbs
I bought this set, and everything was included except the o-rings for the intake boots, which you have to get from an OEM source. He doesn't have the ones for the 550.
 

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I don't know why, but, I don't think they are GS550 carbs.
For some reason I think they may be KZ650?
You need to measure the diameter of carb bore (probably about 1" inside the bore, almost touching slide)
 

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Yeah, they are GS 550 Carbs. Here are some KZ650 carbs that I have installed on a GS550 rack. Notice the air ports in the throat are different:


Here are the GS carbs I rebuilt after abandoning the KZ set:




As I mentioned, the original poster's issue was he had removed a different pilot screw than was supplied in the kit....the GS carbs have an air AND a fuel pilot screw.



Here's his:

 

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How long were those carbs sitting around before you opened em up? I've got some floats that are almost glued in place with old gas...
 

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I have one set that was unusable except for parts. They were sitting for about 6 years with gas in them. I had to get the set in the pictures above from eBay. Ethanol gas is even worse because it attracts moisture then separates and the water layer corrodes metal and the gas layer turns to varnish.
 

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I have a 1979 GS 550 motorcycle ... I bought a set of alternate VM22 carburetor.

An issue occurred in cleaning completed testing. Fourth carburetor (fourth cylinders). after oil leak oil.

After replacing the new float needle valve ... still has the same leak.

Don't know if it's ever encountered a similar situation?

Can solve this problem?

Thank you PICT1993.JPG
 

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I assume you mean fuel, not oil. Have you checked float height? (26 mm) Also, check to be sure the float does not interfere, or rub on the float bowl gasket.
 
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I assume you mean fuel, not oil. Have you checked float height? (26 mm) Also, check to be sure the float does not interfere, or rub on the float bowl gasket.
Testing should be the carburetor float problems. no longer leaking after replace gasoline.

Thanks for the reply
 

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I have a 1979 GS 550 motorcycle ... I bought a set of alternate VM22 carburetor.

An issue occurred in cleaning completed testing. Fourth carburetor (fourth cylinders). after oil leak oil.

After replacing the new float needle valve ... still has the same leak.

Don't know if it's ever encountered a similar situation?

Can solve this problem?

Thank you View attachment 11544
Sounds like a fuel rail leak Permetex #2 on the fuel rail
 
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