• 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.

Need help: air screw adjustment CV carb...

  • Thread starter Thread starter jlvdo
  • Start date Start date
J

jlvdo

Guest
How do you actually adjust the air screw once the assembly is replaced on a 1980 GS750ET??? I've searched the threads long, far and wide and cannot find any ready solution.

HELP!!!
 
Sure I will be corrected if I'm wrong, but CV carbs don't have an air screw. The one screw on the engine side of the carb is a fuel screw. It's a bugger to get to, but with tank off can be done with an extra short screwdriver.
​
 
http://www.thegsresources.com/gs_carb_03.htm


Pics 26-29... air screw. I probably shouldn't have replaced it, but, too late now, at least for carb #1...:cry:. And on further reflection, probably have to replace all of 'em to get uniform...performance? Unless there's a "stock" setting I can get this one back to.
 
You're probably right. I always thought it controlled fuel. Tighter is leaner (on my 81 with CV carbs) and open is richer. You can get back to stock, BassCliff has online manuals and they list the setting. A good start would be tighten til they seat and then turn out 2 turns.
 
Generally 2-2.5 turns out from lightly seated. Before you start messing with the carbs, order a set of carb O rings if you haven't done so,
 
o-rings... check. I've complete rebuild kits.

Anyone have the definitive (if they exist) factory setting for this air screw???
 
Set as Lynn stated, warm up the engine, then tweak the screws until you achieve the highest idle setting. All carbs should be pretty close to each other when it's all said and done.
 
And the pics are wrong in calling them air screws. Those are pilot fuel screws. In leans the mixture, out richens it. If you haven't already removed the others, just count the turns out on them and set the one you removed the same. They should all be about the same within a 1/4 turn or so. Do the highest rpm on them at idle, then once the bike is back together, do a synch and do some chop tests at minimum throttle openings, and adjust accordingly.
 
You're going to have to synchronize the carbs with a 4 way device, and you won't believe the difference. I checked mine tonight because I had a little off idle stumble and an erratic idle. # 4 was lagging behind a bit. After a little tweaking and it runs like an electric motor. But it takes a mercury tube kit or similar apparatus to get 'er done.

On a technical level, the idle screw allows fine tuning of air for the engine's operation at idle while the throttle is closed. You need a richer mixture to idle an engine, about 8.5 to 1 versus 14-1 at cruise. It also smooths the transition from idle to slow speed when you take the grip up a little. Everything has to be balanced in the carb and all 4 have to do the same thing at once. Robert Barr ( a member here) offers the o ring that fits under the needle and without good ones you can't get the thing to behave.
 
Well, I feel better that I'm not retarded and they are fuel screws. Made sense with out being richer.
 
You must log in or register to reply here.
Back
Top