carburetor tuning help please

[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

[rwnielsen]

I didn't read a question there. Did you follow all the directions and settings.. And..?

[nikosg]

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.

[1977jonc]

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.

[Big T]

Did you completely clean your carbs before you rejetted?

[1977jonc]

yes I cleaned all ports and soaked them overnight

[1977jonc]

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?

[nikosg]

I think backfiring can be either from lean fuel/air mixture, or from an exhaust leak.

[Big T]

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

[1977jonc]

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?

[Vexarana]

Take a multimeter and test the resistance of each switch. Sounds like the one you bought is a LOT less than the old one.

[1977jonc]

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?

[1977jonc]

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?

[stetracer]

You have to plug that port or it will make it back fire and not want rev right

[stetracer]

vacuum port on the carbs is open will it make the bike run like crap? do I need to plug the vacuum port?

This was the cause of your problem all along.
I take it your running it on prime?