1977 gs750B jets

[HighCountryGS]

Ok. So after making my eyes bleed searching through this site, google, BassCliff's site, and looking through that chart that i found on here with all the carb specs, I have come to start my first thread.

As the title says, I have a 1977 gs750B. The main jet is #107.5 and the pilot is #17.5. Both have the Mikuni small box inside another box symbol stamped on them. Everythig that i have read has pointed to these not beeing stock jets. Anyways, I have torn down the carbs to clean them in Gunk(wich i have already done) and i have already installed the Cycleorings kit. Have a few questions:

1. What do i need to do about the jets? Use them without any problems? different air filter? different tuning?

2. What does the pilot need t be set at? the box in that table i saw somewhere is blank in that box? I found that the mixture screw is supposed to start at 2 turns out.

I have the gaskets from Z1 ready to go back together.

Thanks in advance for the input.

 

[BassCliff]

Hi Mr. HighCountryGS,

From the "Early GS750" manual on my little website:

Is there an aftermarket exhaust on your bike? Are you running pod filters? It seems the jets are a little larger than stock. But there's not enough information to determine what a previous owner may have done, or why.

For your carbs there are separate fuel and air screws. Generally you'll start with the fuel screw about 7/8 out and the air screw roughly double that. Adjust as necessary. (But I'm no VM carb expert.)

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Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

 

[HighCountryGS]

The exhaust is stock for now. I was think about running pods because the stock airbox isn't in the greatest shape. I have seen some sources that say the stock main is #100 and some say #105. Pilots all seem to say #15 i think.

And by 7/8 out you mean?

Thanks

 

[portdave]

The exhaust is stock for now. I was think about running pods because the stock airbox isn't in the greatest shape. I have seen some sources that say the stock main is #100 and some say #105. Pilots all seem to say #15 i think.

And by 7/8 out you mean?

Thanks

Unless you are running a good flowing aftermarket exhaust keep the stock airbox. You are only asking for headaches. 7/8 out means 7/8 of a full turn out.

 

[chuck hahn]

Cliff, In the service manual on your website..page 78, under the subsection adjusting the carburators, it states that air screws are out 1 1/4 from bottom..then it goes on to explain how to use the guages to balance the cabs. The thing that seems to eludes us is the DOCUMENTED position for the pilot screws..that what i want to know also.. does anyone have anything in printed literature to conclusively shed a light of factuallity on this???? I mean somehweres in a paralell universe Suzuki had to have published the baselines.

 

[Big T]

Cliff, In the service manual on your website..page 78, under the subsection adjusting the carburators, it states that air screws are out 1 1/4 from bottom..then it goes on to explain how to use the guages to balance the cabs. The thing that seems to eludes us is the DOCUMENTED position for the pilot screws..that what i want to know also.. does anyone have anything in printed literature to conclusively shed a light of factuallity on this???? I mean somehweres in a paralell universe Suzuki had to have published the baselines.

No published facts, as the fuel screws were sealed at the factory and considered non adjustable

The 3/4-7/8 comes from the accumulated knowledge of those that messed with their carbs before you

 

[HighCountryGS]

No published facts, as the fuel screws were sealed at the factory and considered non adjustable

The 3/4-7/8 comes from the accumulated knowledge of those that messed with their carbs before you

7/8 of a turn out. Ok. makes sense. So does anyone have a guess as to what to do with the pilot?

 

[chuck hahn]

HIGH COUNTRY..we ARE talking about the pilot jet( the one on the bottom of the carbs). 3/4 to 7/8 out....The other references of 1 out that Basscliff posted and the 1 1/2 out that i had fopund in his online service manual are in reference to the AIR screrw ( the one on the sdies of the carburators ).

 

[HighCountryGS]

HIGH COUNTRY..we ARE talking about the pilot jet( the one on the bottom of the carbs). 3/4 to 7/8 out....The other references of 1 out that Basscliff posted and the 1 1/2 out that i had fopund in his online service manual are in reference to the AIR screrw ( the one on the sdies of the carburators ).

Basscliff's post says 7/8 out on the fuel mixture screw and roughly double that on the air screw. Pilot jet is inside the bowl right next to the main correct?

 

[Guest]

ok so 7/8 on the pilot, 1-1 1/2 on the air scew, and what for the fuel screw? Since BassCliff said i have a seperate air and fuel screw.

EDIT: Basscliff's post says 7/8 out on the fuel mixture screw and roughly double that on the air screw. Pilot jet is inside the bowl right next to the main correct?

That's right. Pilot jet is the #17.5 you posted earlier.

 

[chuck hahn]

You guys are confusing the man..Heres the terms you need to know::

PILOT JET..THE JET INSIDE THE CARB IN THE LITTLE HOLE NEXT TO THE MAIN JET.YOU PUT THAT IN AND GENTLY THIGHTEN IT AND LEAVE IT ALONE

PILOT SCREW..THE SCREW AT THE BACK OF THE CARB BUT NOT INSIDE THE CARBS..AT THE BACK OF THE BOWLS IN THE HOLE.

AIR SCREW..THE SCREW ON THE SIDES OF THE CARB BODIES.

Now heres what you do..Set the PILOT SCREWS at 3/4 to 7/8 out from bottom..then set the AIR SCREWS at 1 1/2 out as is stated in the PDF service manual....Be sure the intake boot orings are replaced..the intake boots themselves are good and not cracked..valves are properly adjusted. vaccuum sync the carbs and do adjustments as neeeded. Your previous post ..to me..indicated that you are confusing the PILOT JET with the PILOT SCREWS ,,, They are two totally different things..

 

[BassCliff]

Thank you chuck hahn!

Yes, screws get adjusted. All jets get snugged into their respective receptacles.

Fuel screws and air screws are set at a starting point and adjusted from there. I don't think I've ever seen any true factory recommendations because every engine/carb arrangement is a little different, even on the same model, due to tolerances and variables.


Thank you for your indulgence,

BassCliff

 

[chuck hahn]

Agreed Cliff. These are just as "starting points" as you pointed out. I thought i should have clarified the terms for the man..He seemed to me a bit confused between the pilot jet and the pilot screw. Wasnt meaning to step on anyone elses efforts..I really try to keep it at the K.I.S.S. level ( Keep It Simple Stupid)!!!

 

[BassCliff]

Wasnt meaning to step on anyone elses efforts..I really try to keep it at the K.I.S.S. level ( Keep It Simple Stupid)!!!

I'm glad you took the time to clarify the terminology. Thank you!

Thank you for your indulgence,

BassCliff

 

[HighCountryGS]

You guys are confusing the man..Heres the terms you need to know::

PILOT JET..THE JET INSIDE THE CARB IN THE LITTLE HOLE NEXT TO THE MAIN JET.YOU PUT THAT IN AND GENTLY THIGHTEN IT AND LEAVE IT ALONE

PILOT SCREW..THE SCREW AT THE BACK OF THE CARB BUT NOT INSIDE THE CARBS..AT THE BACK OF THE BOWLS IN THE HOLE.

AIR SCREW..THE SCREW ON THE SIDES OF THE CARB BODIES.

Now heres what you do..Set the PILOT SCREWS at 3/4 to 7/8 out from bottom..then set the AIR SCREWS at 1 1/2 out as is stated in the PDF service manual....Be sure the intake boot orings are replaced..the intake boots themselves are good and not cracked..valves are properly adjusted. vaccuum sync the carbs and do adjustments as neeeded. Your previous post ..to me..indicated that you are confusing the PILOT JET with the PILOT SCREWS ,,, They are two totally different things..

Great reply! THANK YOU! i had it right in my head and i guess it came out wrong. Everyone seems to have there own term for these things.

Anyways...Do you think i just need to leave the jets that are in there alone? since they are not stock it seems? If i am correct they are only one size up 107.5 and 17.5?

 

[HighCountryGS]

The bike is a 77. no telling what the jets came out off. I know they are Mikuni because of the stamp. I opened up the carbs and half of the the o-rings were missing so they could have been changed, but bike is all stock. That problem has been solved thanks to cycleorings.com.

 

[chuck hahn]

Well my 77 is all stock as well..I am pulling the carbs off tomorrow to do a bit of clean up and adjusting..Tell you what, i will look at the internals and post whats in mine..fair enough???

 

[HighCountryGS]

Well my 77 is all stock as well..I am pulling the carbs off tomorrow to do a bit of clean up and adjusting..Tell you what, i will look at the internals and post whats in mine..fair enough???

If you would i would appreciate it.

 

[HighCountryGS]

High Country..I just opened the carbs up and the MAINS are 110 and the PILOT JETS are 17.5 ,,,Clip in the middle groove

So did they put all different sizes of jets in from the factory? or did you put those 110's in?

I'm not trying to seem stupid, but everywhere i look it seems like there are dIfferent jets in these bikes. Some 100,105, i have 107.5 and you have 110. Then i have seen some 15 pilots and we both have 17.5 pilots. My head hurts...

 

[rustybronco]

Hope this helps...
http://thegsresources.com/_forum/showpost.php?p=324909&postcount=43