1978 550 problem

[garydog]

I have a 78 550 that is not running on #3.

Craigslist non runner
I did not take off the carbs
Older fuel left in tank
flush tank now new fuel
3 other cyls running well
Took off top of carb and filled with carb cleaner and let sit a few min. ran on #3 for about 2 min and now back to 3 cyl.
good spark and the bowl is full of fuel.
Plug is black with a little wetness/blackness showing.

Can I do anything short of taking off the carbs. If so it seems that the airbox prevents much movement unless I do not see how to unbolt the box.

Thanks Dan

Intro: I have been riding and fixing for 20 years. I was a gt rd guy until the last couple years. I had a gs850 last summer and now I am on to the 550.
I can usually find my own problems and fixes but this one is harder cause I really do not want to pull the carbs but I think I may need to. I live in the Black Hills about 10 Min from sturgis.
I also love scooters. Baja Chetak is the current ride.

[cowboyup3371]

Howdy and welcome to the site; Basscliff will probably stop in later today to officially welcome you. But for now, your best bet is to remove them and ensure everything is up to snuff. Check out this site - http://members.dslextreme.com/users/bikecliff/ for everything you will need to know.

[Adler]

pouring carb cleaner into the top of the carbs wont get any carb cleaner into the jets, you may get lucky if you run some product like seafoam in the gas, but on a bike this old you really should be doing a complete teardown.

[BassCliff]

Greetings and Salutations!!

Hi Mr. garydog,

Yep, sometimes you just gotta do it right. You can try a good dose of SeaFoam, BG 44K, or a Techron additive to try and clean the carbs. But if #3 is really gunked up, you'll have to get in there and clean it properly. There is a link to a well done carb cleanup series in my "mega-welcome" and on the GS Resources homepage (link at the bottom of this page). You'll want to replace all of the internal carb O-rings too. Get a set from http://cycleorings.com. On the 550 it's less convenient getting the carbs out than on other GS bikes. Sorry about that. Anyway, let's get started.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", the Carb Rebuild Series, and the Stator Papers. 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