• 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.

carburetor tuning help please

  • Thread starter Thread starter 1977jonc
  • Start date Start date
1

1977jonc

Guest
I have a 1977 gs750 that I installed a 6sigmaracing jet kit on and I need help tuning it. they suggest that I set the air screw to 2.5 turns. fuel screw is at 1 turn. I have a vance and hines 4to1 exhaust and air filter pods. the main jets are 117.5 on cylinder #1 and #4. and 120 on #2 and #3. please help. wanting to ride again so bad
 
I didn't read a question there. Did you follow all the directions and settings.. And..?
 
What is the problem with the way its running? why have you got the fuel screw at 1 turn? where are your problems?
No one can help you tune it with the information you have provided.
 
it is bogging down at slow throttle and shutting off with a quick throttle. I can screw in either on of the fuel or air screws and the bike will still run. my understanding is that it should kill the bike? only the air screw on the #2 carburetor will shut off the bike if I screw it in. I also pulled out the spark plugs and they came out wet. I followed all the directions in the jet kit packet.
 
Did you completely clean your carbs before you rejetted?
 
I just took the air pods off and she's running much better but has a bluish white smoke coming from the exhaust and she's backfiring. does anyone know what this might mean?
 
I think backfiring can be either from lean fuel/air mixture, or from an exhaust leak.
 
I think backfiring can be either from lean fuel/air mixture, or from an exhaust leak.

You are correct

Check the exhaust system, then your spark plug color

Also, try turning the air screws in 1/2 turn and see if the backfiring lessens
 
ok thanks for the help guys. I had to adjust my throttle and my floats. shes running much better but I cant ride yet cause my lights are being screwy. they don't sell a light switch for the 1977 GS750B models anymore so I had to buy a light switch for a 1977 GS750C model. plugged it in cause it looks compatible and my headlight started to smoke and the light switch wire got pretty hot. I unplugged it before any real damaged happened. any suggestions as to what might have caused it to do that?
 
Take a multimeter and test the resistance of each switch. Sounds like the one you bought is a LOT less than the old one.
 
found the electrical problem. had my hot wire grounding on the frame and causing all sorts of issues. bike runs but she bogs really bad and dies when I do a quick throttle. shes running a little rich, would that cause the bike to have a bad response?
 
also this might seem like a dumb question but if I have a new tank on the bike running just straight gravity fed and the vacuum port on the carbs is open will it make the bike run like crap? do I need to plug the vacuum port?
 
You have to plug that port or it will make it back fire and not want rev right
 
Last edited:
He just had a small air leak... Its how we learn. Nice help there Mr. Stetracer...
Curt
 
He has not come back and said it is fixed but I would bet a dollar to a doughnut that's it.
 
yes I went ahead and put a cap on the vacuum port and the bike is running great now. still having some electrical issues but thanks everyone for the help!
 
Back
Top