Gs650 carbs on a gs550

[SILENTxIRIE]

I have found an offer on craigslist for 1981 gs650 carbs with stage 3 dyno jets and pods, I am wondering if they would fit on my 81 gs550. Any info would be greatly appreciated, thanks!

[tom203]

I have found an offer on craigslist for 1981 gs650 carbs with stage 3 dyno jets and pods, I am wondering if they would fit on my 81 gs550. Any info would be greatly appreciated, thanks!

Sure, but main jet would likely be too big- what's your current setup, pods? non stock exhaust? do you like experimenting?
What's wrong with your current carbs?

[SILENTxIRIE]

my current set up is stock airbox with a 4 to 1 exhaust but it deosnt want to idle, I found a guy on craigslist selling the 650 carbs with pods already jetted so I figured id switch them out and Id be good to go.

[Steve]

Carbs with pods that are "already jetted" are really suspect.

You need to know WHAT they are jetted for and what jets you will need.

The jetting for the 650 will be a bit different than your 550.

At least the carbs will be the proper carbs, whether the jetting is correct or not.

How long have you had your bike?

Has it ever idled for you?

Have you tried cleaning the carbs and replacing all the o-rings?

That is the most-likely cause of your idle issues, no need to spend a bunch of money for carbs.

.

[BassCliff]

Greetings and Salutations!!

Hi Mr. SILENTxIRIE,

Yes, proper maintenance is the key to a safe and reliable 30 year old motorcycle. It all starts with properly cleaned carbs, valve adjustment, and properly serviced electrical/charging system. Details below in your S.W.A.G.

If you are here you probably have a 30 year old motorcycle that needs about 20 years worth of maintenance. You'll find all kinds of helpful tips, procedures, manuals, diagrams, "how-to" guides, etc, in the links below. Let's get started.

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Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. This is what NOT to do: Top 10 Newbie Mistakes. Now let me roll out the welcome mat for you...



Please Click Here For Your Mega-Welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[tom203]

Like others have said, it will be less hassle to deal with your current carbs. Problem idle is very common with dirty carbs the #1 suspect. Head to the info library in Basscliff's link.
If this bike is new to you, and you want to enjoy it, maintenance is calling!

[SILENTxIRIE]

Thanks for the welcome, I am a previous gs450 owner and know the ups and downs of maintenance and getting a bike to run properly but I am at a loss to this one, Ive cleaned the carbs thoroughly and I have no intake leaks but it still wont idle. Im assuming I might have to bump up jet sizes to accommodate the 4 into 1 exhaust. What do you guys think?

[Steve]

You don't need bigger jets to get it to IDLE, regardless of your intake or exhaust plumbing.

My guess is that the carbs still need a good cleaning.

Please tell us exactly how you cleaned them.

.

[Toasty]

From what I've heard from people here is that just a 4-1 shouldn't require additional jetting... What is your bike doing at idle? When you cleaned the carbs, did you take them apart and soak the parts in carb dip for at least 24 hours, then use new viton o-rings? You will probably have to adjust the idle air screws too. Are the valves in spec? Is the petcock filter clean? Are you running an inline fuel filter?

What kind of air filter are you using btw?

[SILENTxIRIE]

I entirely stripped and dipped them, new gasket and viton o-rings. Valves are to specs, clean petcock, no inline filter. Don't remember what air filter, Ill check tomorrow. I got it to idle today and stay on by adjusting the idle air screws to 4 turns out but it runs sluggish, very bad at 40 mph+

[wegs426]

I called the dynojet jet technician today in regards to my setup.

From the phone call the 650 stage 3 kit comes with 2 different main jets and no pilot jets (says air screws can be backed out enough). It does however include a spacer and new needle, plugs for the main air corrector, and a drill for enlarging the slide air hole.
The main jets are their part numbers: dj160 and dj155. The large one is to be used with 4-1 and the smaller one without.
He said the dj160 is about equivalent to a mikuni 155. To me this seems really high (18 sizes larger than the stock 110) even for open 4-1 with pods.

It will definitely be to much for a 550. 550's have a 92.5 stock main jet.

If those are the only carbs you can find you could probably make them work with pods, and a pipe by sizing to a 107.5-115 main jet depending on how restrictive your muffler is. You will probably have to move the needle down a couple of spaces as well as turning in the air screws (you probably won't need a smaller pilot jet as the 650 is only one size larger than the 550). Expect to do some testing to fine tune it.

[SILENTxIRIE]

I've ditched the 650 carbs idea, I only wanted it for the jets and pods hoping it would be an easy swap. Now I am concerned with getting my 550 to run right with the stock air box and V&H 4 to 1. I will be ordering size #95 and #97.5 jets just in case I need to go higher. Are all 4 main jets sized equally or are the #2 and #3 carb jetted higher?

[SILENTxIRIE]

And something I've noticed about this forum is that the begging of a thread sometimes changes from the first page to the last, is this normal of the forum or should I be getting a new computer?

[BassCliff]

Hi,

You'll find a chart with most of the stock carb specs on my little website.

By default the forum posts show the newest on top. You can change this behavior and add more information to you profile using the "User CP" in the upper left corner of the page. Add location, signature file with bike year and model, etc.

Thank you for your indulgence,

BassCliff

[tom203]

I've ditched the 650 carbs idea, I only wanted it for the jets and pods hoping it would be an easy swap. Now I am concerned with getting my 550 to run right with the stock air box and V&H 4 to 1. I will be ordering size #95 and #97.5 jets just in case I need to go higher. Are all 4 main jets sized equally or are the #2 and #3 carb jetted higher?

Jets are the same size. Honestly, I'd head to Basscliff's and review the carb cleaning stuff. You said you completely tore them down, but did you blow and poke out (carefully!) the nasty little holes in idle circuit?make sure that the pickup tube for "choke" is clear and make sure "choke" plungers are not sticking?