Help Identifying Correct Jets on a 77 GS750

[Azul the Cat]

Previous owner had pods, and a shop re-jet the carbs with 115 main jets I put the stock air box back on, and I'm looking to replace the main jet with a genuine Mikuni jet in the stock size. So poke around to see what I can learn here, and then I head over to Bass Cliffs site and read through the chart on OEM jets sizes, and learn that the early 750's had different jetting depending on when it was made. The frame tag said it was manufactured 7/76. and I have pics of the stamped numbers on the engine and frame in the link below. I must be looking at the wrong numbers since I didn't see those corresponding numbers, so I thought I would go the other way and check the pilot jet size. I pull the pilot jet, and it's a #20 Mikuni jet. Now this is where I get really lost since according to the chart on Bass Cliffs site that should be 22.5 or 27.5. I know for the main jet I need either 105 of 97.5, but do I also need to look for new pilot jets? Would I need a 22.5 or a 27.5 pilot jet?


Here's a link to a few more pics of the carbs. https://imgur.com/a/kJDk7Ja

 

[Forden]

This thread posted a while back has a service bulletin that may be of help:
https://www.thegsresources.com/_for...-Screw-Technical-Service-Bulletin-From-Suzuki

 

[Azul the Cat]

This thread posted a while back has a service bulletin that may be of help:
https://www.thegsresources.com/_for...-Screw-Technical-Service-Bulletin-From-Suzuki

Thanks. Where would I find the numbers on the carb they reference, like 45010 or 45011?

 

[zed1015]

The carb reference number is on the carb flange where it bolts to the back plate.

 

[Azul the Cat]

Thanks for your help!

 

[Nessism]

The factory manual says 100 main and 15 pilot. The main can be bumped to 102.5 and the pilot to 17.5 if needed. With Suzuki's VM's there is a lot of tuning available through the pilot screws though so jet changes shouldn't be needed unless you have modified the bike.

 

[Guest]

The carb ID number will be here on the #4 carb. It’ll be faint but it’s there.

 

[Azul the Cat]

The carb ID number will be here on the #4 carb. It?ll be faint but it?s there. View attachment 63615

This was a huge help. I was having trouble finding it on the flange. I found it now, and confirmed them to be 45020