what are those Jets?

[Rustybux]

I have a 78 GS750. What are the jets under the carb next to the float bowls and what are the jet settings as far as how many turns out? Also the jet on the side of the carb.
I'm wanting to put 4-into-1 headers on it and does anyone have a rule of thumb on how much bigger main jet to install. I hate to buy half dozen jets and just hit and miss.

thanks.

[psyguy]

maybe this could help

http://www.thegsresources.com/_forum/showthread.php?t=73723

welcome

[Nessism]

Pilot fuel screws on bottom, pilot air screws on top.

VM carb info... http://www.thegsresources.com/files/vm_carb_rebuild.pdf

[KEITH KRAUSE]

I have a 78 GS750. What are the jets under the carb next to the float bowls and what are the jet settings as far as how many turns out? Also the jet on the side of the carb.
I'm wanting to put 4-into-1 headers on it and does anyone have a rule of thumb on how much bigger main jet to install. I hate to buy half dozen jets and just hit and miss.

thanks.

Stock main for your model is 102.5
If the 4-1 pipe is quality and the only mod, try 5 to 7.5 larger on the main. Rule of thumb is to go richer and work your way back. I can't say if 5 is enough so I'd try a 110 first. Test performance at full throttle and chop off and read the plugs.
Solid 1/3 throttle test will tell you if the jet needles must be raised a little, in your case, possibly 1/2 position.
Stock 15 pilot jet will be fine.
Pilot fuel screws underneath can vary a little straight from the factory. I'd probably try 3/4 turn out from LIGHTLY seated and test.
As for the side air screws, they are adjusted using the highest rpm method. They generally end up 1 1/2 to 1 3/4 turns out if the bike is tuned/running correctly.