• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

carb air screws

Redman

Redman

Forum Guru
Super Site Supporter
Past Site Supporter
Got the carbs off my 82 GK (that I just got, dont know much of history). Am following the directions in the "carb cleaning series" in "the garage".
Am taking out the various jets for cleaning with carb cleaner spray. I get the idea that the main jets and pilot jets are just jets that screw into place, and are not really an adjustment (well, other than changing to a different size jet), correct?

On my carbs it seems that there is some sort of cover/plug over the 'air screws'. Looks like the cover/plug has has a small hole such that can get a wire or something to pull it out. That correct? This doesnt seem to be addressed in the "carb cleaning series".

Isnt that air screw the major thing that is adjusted when carbs are "balanced". So if those cover are still in place, doesnt that mean no one has ever balanced these carbs in 24 years (but only 29k miles)? Covers look nice and undisturbed.

I am not really finding anything gummed up or dirty so far, so maybe is no real need to get into this air screw..?

I know that some say the carbs need to be rebalanced if you touch anything, but these air screws are really the most critical, correct? Certainly will need to rebalance if those air screws are distrubed, correct?
 
Air Screws:
http://www.thegsresources.com/images/carbs/007_AIR%20SCREW%20LOCATION.jpg

Ok, so I am an ignoramous, I see the Zuki manaul doesnt mention the air screws in the carb balance procedure.

As a mater of fact the Zuki manaul doesnt hardley mention those air screws, dosnt even identify them, like they didnt exist or something. Oh, so, we aren't suppose to know they are there. Well, now that we do know they are there.. they are an adjustment, correct?
 
Last edited:
You have three jets to clean in each carb. The pilot jet is under the rubber plug next to the main jet. Those are caps over the air screws to keep anyone from messing with them after the factory adjusted them for emissions. If you're careful, you can easily remove them by drilling a hole in the center. Be sure to barely pierce the cap so you don't damage thr screw head under it. When I did mine, each cap sort of spun up the drill bit and removed itself.
 
To balance the carbs you use the screws and lock nuts on the throttle linkage. And according to the manual it tells you to adjust the sync tool to have the center two carbs a little lower. The MotionPro sync tool is not adjustable. So when you sync the carbs you want the center two a little higher to compensate for the Suzuki adjustable tool that you are not using! You have to read the part of the manual about 4 or 5 times to get what it wants you to know.

Also when you adjust the fuel/air mixture screw, you want to screw them in and out to acheive the highest rpm!

Good luck!
 
Here's what I've found out after dealing with problems with my bike having really strange issues. All was pretty much fixed by messing with the air screws on the engine side of the carbs on top

"Well guys, I fixed my own problem again. It turns out the air screws in the back really do help a lot. The difference between 3 1/4 turns out and 1 1/2 turns out is enormous. The bike still could probably use a carb synch for the final tuning, but the problem is almost totally gone now.

It has a flat spot below 15mph in first, but beyond that it pretty much goes. I can't go full throttle until it's halfway up the revs (by ear, tach doesn't work), but it pulls insanely now. When it hits 30mph or so, it tries to remove me from the seat."

That's an exerpt from my thread in tech about a common problem that apparently nobody had any advice about.
http://www.thegsresources.com/_forum/showthread.php?t=87332
 
Let me get this right. Since the two middle cylinders get hotter than the two outboard ones, the middle ones would have a higher vacuum for a richer mixture which would mean that on a mercury sync. tool the two middle levels will be slightly higher than the outside ones. Is that right
 
Redman, the screws you're describing on your CV carbs aren't air screws, they're mixture screws. They assist the pilot fuel jet. They're the fine tuning for the pilot circuit. They allow you to increase/decrease equal amounts of air and fuel. Turning them out further, effectively richens the circuit.
They should be adjusted by using the highest rpm method. Other than that, which should be done before a vacuum synch (if you think they've been moved from their factory settings), they have nothing to do with the carb throttle valves being in synch.
No way to really tell if they've been moved or not, based on if the factory caps are still on. The old factory sealant can chip away and be completely gone too. The factory usually wipes some on the threads (makes them hard to turn) and the top of each screw (the assemblers way of marking the screws as "set/tuned"). A PO could have replaced the caps after moving them. Generally, your mixture screws will be about 1 to 2 turns out from the factory. 1 1/2 being my closest estimate. They may be stiff and the heads can strip easily. Unless you have some idle/warm up issues, I see no reason to mess with them.
 
OK, Thanks guys. Thanks Keith. I now understand that what the "carb cleaning series" calls the "air screw" is not what is used to "balance" the carbs. I now understand that balancing has to do with those adjustments on each carb throttle plate (maybe called 'butterfly').

The best description of the carbs that I have found is in my factory manaul for my 850G. And I see, as Keith has described, that the pilot screw is part of the pilot circuit (or "low speed" or "slow system"). And I see that is an adjustment. That pilot screw and the throttle plates linkage are the only adjustments. Everything else is just a jet that goes in its place with no adjustment.

In the past I have taken off carbs and taken off the bowls and taken out that rubber plug and then spray carb cleaner in all the jets and ports that I could find. I didnt unscrew anything out of concern for messing with adjustments.

But now with this better understanding (and bike a I bought that runs like crap) I took the carbs down into the basement and have taken out the floats, the float seat/needle, the pilot jet, the main jet, the main needle jet, and the main needle/slide. Have not taken carbs apart from each other and have not messed with the pilot screws nor the starter "choke" plunger. Have found some of the little ports on the jets did need cleaning. Also found that there was no screens on the float valve seat. And found some of the float seat orings were so small and hard that they probably were not sealing. SO I have those screens and o-rings on order. And have let the jets soak in carb cleaner for a day and then cleaned out with a small wire. Have shot carb cleaner back up that wee little bitty hole back into the pilot screw, and thru every place else I could find.
So ... I suspect things are gonna be different now, well, maybe not untill next time its upper 30s or 40 degrees, so can work in garage to reinstall the carbs . . may be a few weeks --heavy sigh--

Oh, and I found out why its not a good idea to put the parts in a stryafoam egg carton. The gas and/or carb cleaner disolves the strofoam and then reforms on the part.

Well, I have some snow to shovel.
Thanks again.
 
Last edited:
Thank you

Thank you

I just wanted to give a wuick thank you for this thread. I've been messing with my carbs for a few weeks trying to get my 1980 gs550 running right. It was running way rich, and not idleing right. Come to find out that my mixture screws were anywhere from 4-6 turns out! The Haynes manual that came with the bike was absoloutly no help, as it didn't even identify the mixture screws. Now it's running mint, and I'll be on the road this week. If any of you guys are ever in Jamestown, RI, stop in for a beer, I owe you one!
 
For those of you doing your carbs The BS series NEED TO BE soaked in carb cleaner for 6-8 hours if possible, Get an O ring kit from Robert Barr it's all you usually need to repair your carbs. If you are carefull you can reuse the float bowl gaskets
 
Hey Redman, I just drilled out the caps to my mixture screws. I did it using a dremmel which worked great for two reasons. 1)didn't have to take the carbs out and wrestle them back in. and 2) I thought (at least) it was easier to control as to not damage the screw. Though a word of caution, after I got a sufficient hole to put a screw driver in the wedge out the rest of the cap, I chipped part of the collar around the screw. Luckly didn't affect anything, but was unexpected. Later and good luck!
 
You must log in or register to reply here.
Back
Top