lean jetting from factory?

[s276l]

Hello All,

I bought a 1982 gs550 as a winter project. I am cleaning the carbs and was told the factory jetting was lean which can cause long/rough warm ups and subpar performance. Everything on the bike is stock and I dont plan on doing any modifications. Should I change the jetting or leave everything stock? If I should fatten things up what jets and by how much?

Thanks in advance,
Sean

[Octain]

Welcome to the forums!

[Steve]

Usually, it's just the pilot circuit that needs to be richened up on a stock bike. Since you say it's a project, we'll assume that you plan on taking the carbs apart and cleaning them according to the guide in the Garage section. One thing you will want to be sure to do is to remove the caps over the idle mixture adjustment screws. Turn the screws in GENTLY until they stop, counting the turns on the way. There is a good chance that it will only be about 1 1/4 turns. Most of these bikes work MUCH better with the screws at least 2 turns out, so, when you re-assemble your carbs, start at 3 turns, then, when the bike is warmed up and off "choke", slowly turn the mixture screws in until the engine slows a bit. At that point, back the screw out about 1/8 turn, move to the next screw. When you are done, try them again, just to make sure they are right. Turn the engine off, turn each screw in until it stops, again counting turns. Record that number for future reference, turn the screw back out. Note that they won't necessarily be the same number of turns out. Should be close, but may not be exact.

You should be getting a "Welcome Wagon" bit from BassCliff soon, read it carefully, there is a LOT of information there, including links to all the pertinent stuff.

.

[BassCliff]

Greetings and Salutations!!

Hi Mr. s276l,

Yes, these were jetted pretty lean from the factory for the USA's emissions standards at the time. But if everything is clean and properly maintained there shouldn't be any major issues. After you've done all the required maintenance, if you notice any flat spots through the rev range, then we can address that issue. Usually this involves only shimming the needles. Anyway, let me share some GS lovin'.

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", "Top 15 Tips For GS Happiness", 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

[s276l]

Thanks for the warm welcome everyone! This is my first go at rebuilding an older bike and I have already learned so much through this site.

Steve, you just answered another question I was going to ask about the idle mixture screws. There are 2 on each carb correct?

Thanks

Sean

[Don-lo]

For your 82 550, there is only one adjustable mixture screw on each carb, on the top/front, and it came from the factory hidden under a cap. There are good directions in the carb-clean series to help you access and adjust these screws.

Yes, jetting from the factory was very lean. Here is a link to an 82 comparison article about the sporting 550s, and it includes the GS550 Katana. You should notice on pages 6 and 9 that they feel the Suzuki is nearly unrideable until the needles are raised, but it is still picked second best overall.

http://i350.photobucket.com/albums/q407/Don-lo/gs6.jpg

http://i350.photobucket.com/albums/q407/Don-lo/gs9.jpg

[Steve]

If you have an '82, you will have four separate carbs, and they will only have one mixture screw per carb.

However, if you have an '83 that might have been made late in '82, it will have two twin-throat carbs. In that case, yes, they would have two per carb.

Which one do you have?

.

[s276l]

Don-lo, thanks for the info and the old article, very cool.

Steve, I have four seperate carbs. I see two caps on each carb, I assume the cap I need to drill out is the one closer to the top of the carb? A detailed pic of what I am talking about can be found here, page 15 http://www.mtsac.edu/~cliff/storage/...ing_Series.pdf

Do you guys replace the fuel inlet tee? Its rubber coated and has no orings to replace. Mine looks okay and fits snug into the carbs but id rather not chance it if its a common issue.

Sean

[Steve]

Yes, that is the one that is covered by a cap that needs to be removed.
Unfortunately, the author of that otherwise wonderful guide used the wrong term for the screw. It is NOT an "air screw", it is an "idle mixture adjustment screw".

Ok, that is one cap, where is the other one you see?

By the way, do you have a little hole in the center of that cap or is it totally solid? Either way, when you go to drill, do it slowly and carefully. With luck, the cap will catch on the drill bit and twist out. If not, use a drywall scrwe in the hole and pull it out with that.

.

[Octain]

Don-lo, thanks for the info and the old article, very cool.

Steve, I have four seperate carbs. I see two caps on each carb, I assume the cap I need to drill out is the one closer to the top of the carb? A detailed pic of what I am talking about can be found here, page 15 http://www.mtsac.edu/~cliff/storage/...ing_Series.pdf

Do you guys replace the fuel inlet tee? Its rubber coated and has no orings to replace. Mine looks okay and fits snug into the carbs but id rather not chance it if its a common issue.

Sean

As for the rubber coated T, if it makes you feel better I have heard of others wrapping the ends that insert into the carbs with teflon tape. I have a set of VM's I did this to but have yet to run em.