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Can anyone help tell me a good starting jet for a 79 GSE 550 with air filter pods?

M

Markofalltrades

Forum Apprentice
Greetings my first port,
I bought a 500$ 1979 GS550E last week. When I tried to start it she ran and then quit. The carb is a mess. I have repaired several minor issues and am now ready to sonic scrub the carb and rebuild it. The bike has filter pods on it but I do not know if the 47.5 main jet is stock or rejetted (correctly). I can tell it has had several owners who likely gave up on making it run. Does anyone know the stock jet sizes and a good size to start with to rejet it?? Do I need to rejet all jets or just the main? Would it be better to just try and find a stock air filter? The exhaust does look stock. Will the carbs need to be balanced?
 
https://gsarchive.bwringer.com/

Do a full carb rebuild, following the tutorial for VM carbs... https://gsarchive.bwringer.com/bikecliff/images/vm_carb_rebuild.pdf

Be sure to replace all the O-rings, and don't shortcut the process, or you will be back doing it again.

Download the factory manual for your bike, and use the published specs, and those on a site like partzilla.com, to learn what the stock jetting for your bike is supposed to be. Then compare your jets to stock and/or change them to stock.

last thing, buy Air Jet correction jets from Zed. They will make jetting with pods easy. It can be done without these parts, but you will be stuck in the world of trial and error in determining the best jets. Also, buy proper pods, Uni, K&N, or maybe some APE pods (if they make an appropriate set). China pods like those sold on Amazon are junk. Stay away.
 
Thank you for the responses and links. It has a main jet of 47.5 Looks like someone already jetted it. From your link it is stock at a main jet of 40. This could balance out though. Going to be interesting and I will message back after the carb kit arrives. Or if someone responds before then with any more tips.
 
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No GS bike that I've ever seen uses a 47.5 main jet.

I provided you a link to a site with a free factory manual download, along with a tutorial on how to rebuild the carbs. My signature provides a source for carb O-rings. Yes, you don't seem to have explored any of this information.
 
When I purchased the carb kit for a 79 GSE 550 it did not match.

​
I was able to identify it after your link and it was indeed a GS550 carb originally though I thought someone had used a GS650 carb in it.
This is what it actually has in it.

There are other oddities about it too. Like the rubber round disk that goes under the gasket. Only the GS750s and GS1100 kits include it. (Do I need it?)​​
 
Most GSR folk has sworn off "carb kits", as inferior and unnecessary in most cases. Keyster makes half way decent parts, and OEM, of course is good. Most others, including K&L, I won't use.

Those round donut rings are to seal a metal plug that's pressed into the carb body during the manufacturing process. The passage is necessary for cutting tool access during manufacturing. Most of the time, those plugs never move. Key word, "most of the time". Sometimes they fall out and get lost. They can't get lost on the bike, that happens when rebuilding the carbs. I found one sunken on the bottom of my carb dip can, for example. If you don't have those seals, I wouldn't worry too much. Maybe an O-ring could take their place? Or cut one from rubber sheet? Welcome to the world of 40 year old motorcycles!
 
I was seriously considering just that. Reuse what I can clean and only use the gaskets and worn parts. Fortunately once I removed the crud the inner carb parts are pretty much good to go. I think if the float springs were good it would have roughly started. Someone has cracked this carb open in the past. I used JIS screw drivers but even so there were no issues taking it apart regarding striping anything. The bellows look good and I am hunting for a good High-temp synthetic &High-temp bearing grease. I will be putting the carb together this weekend after I thoroughly reread the VM Carb Rebuild PDF that you sent me. (Just in case I missed something it is truly an excellent compilation. I think it deserves to be printed)
Regarding the round rubber doughnut pieces.. I could not find 2 of them. Maybe they were lost by someone else. I have a rubber sheet I can make one out of. Can't wait to hear this bike wake up for the first time after many years.
 

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The only thing on set of carbs that needs grease is the throttle shaft bushings. You don't need special grease for those.

Not sure what "bellows" you are referring to.

Be sure to remove the rubber carb boots that bolt to the head. Flex them under magnification, and if you see any cracks, replace them. Or, just replace them straight away. Old rubber parts are a failure waiting to happen.
And be sure to replace the large sealing O-rings on the boots. Actually, all the carb O-rings should be replaced straight away, regardless. Do the job right the first time.
 
Assuming your carbs are the correct VM22's with the kidney shaped passage at the 10 o'clock position in the mouth of the carb -

The pilot jet should be a size 15 and an 80 main jet as stock.

When running without a stock airbox you should fit air corrector jets to cure the off idle hesitation/ bogging.

With these fitted the pilot jet and needle position must ALL remain stock with only an increase on the main jets to 92.5 needed.
 
Something just struck me, through this thread there has been a lot of confusion about what carbs are involved. In one post it's VM22 carbs for an early GS550, and later there is mention of GS650, and carb body plugs falling out.

Just to be clear, the early carbs are VM, and don't have those plugs discussed earlier. Too much confusion. Post photos.
 
Today she started right up. What a beautiful sound.
It would not stay running without a bit of throttle. It could be idle setting but also may be needing a retune.
 
And now it wont start again. After it started earlier it was dripping gas and eventually had a really forceful backfire. (it was flooding) I replaced the aftermarket float needles with the cleaned originals that appear to be working well. I then checked and realized I needed to adjust the float height per specs 22.4 mm. Bowels now fill with gas and do not overflow but spark plugs are dry and of course it wont start. Thoughts?
 
The description of the bike says " '79 550", but all the carb references sound like BS series carbs found on '80-and-up GSes.

I'm wondering if it is indeed an '80 bike that was made in late '79?

Depending on the location of original sale, it might have been titled as a '79, even though it was sold as an '80.

I'll agree with other posters, ... THIS THREAD IS WORTHLESS WITHOUT PICTURES.

It would help to get a close-up pictures of the side of the bike that shows the carbs.
Bonus points for a shot of the VIN tag on the steering neck.

.
 
Markofalltrades youjust posted pic of CV carbs on a new thread. That’s the info folks have been asking for here. Your choke problem you described there may be relevant to this conversation as well. I would suggest you include that info here too and delete your other thread.
 
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