78 GS 1000 C specs needed

[chuck hahn]

1978 GS 1000C with vm 26s..I need the settings for the fuel screw and the air screws..everything i read says the fuel screw is "PRESET". I plan on pulling the carbs and checking them over becuase i am getting really crappy gas milage ( around 23 MPG). If i pull the jets out i wanna know where to set them as per factory. I havent taken the carbs off as of yet and dont know if anyone had done anything to the bike before i got it. I want the info before i take them off. Anyone with experience or a chart showing the base settings please PM me the info..Thanks, Chuck Hahn.

 

[hampshirehog]

The fuel screws are normally around 5/8 to 3/4 turns out from lightly seated and the airscrews about 2 turns out. Check for little dimple marks next to the the screws on the carb bodies - Suzuki put these there when they made the carbs and they might still show.

 

[Big T]

Look at the top of the page, there's a sticky with all the carb specs

You don't adjust the jets. If they are not the stock size, change them back

 

[Nessism]

There is no published spec for the screw settings (for the US market anyway), and I’d question any you find anyway since emissions test standards, not best driveability, influenced the settings.

I’d start at ? open on the fuel screw and 1.5 on the air screw and tweak from there until the bike is running the way you like.

 

[srsupertrap]

If your GS1000 is getting 23 mpg I would bet the PO has messed with the carbs. I don't see how messing with those two screws would drop the mpg from mid 30's into the low 20's.

Using oil :?:

 

[chuck hahn]

The bike doesnt use any oil and yup i am suspicious that someone has been in the carbs. I need the info on what is the stock main jet size, what slot main needle gets the clip in, what are the basic air and fuel screw settings..And to the one that suggested the sticky..tried that for hours and the search feature too..didnt come along anything. And if i dont know what the stock main jet size WAS..then how will i know if whats there is stock or not?? How will i know if the clip for the main needle is on the right spot? See where i am going with all this. I need as much info as i can or i just wont be able to tell whats going on in there once i open them up.

 

[rustybronco]

Warning!!!! old spark plugs still needed...

 

[chuck hahn]

YEAH YEAH YEAH... I know. Just for craps and giggles..does that service manual that came with your bike have anything listed???

 

[srsupertrap]

The bike doesnt use any oil and yup i am suspicious that someone has been in the carbs. I need the info on what is the stock main jet size, what slot main needle gets the clip in, what are the basic air and fuel screw settings..And to the one that suggested the sticky..tried that for hours and the search feature too..didnt come along anything. And if i dont know what the stock main jet size WAS..then how will i know if whats there is stock or not?? How will i know if the clip for the main needle is on the right spot? See where i am going with all this. I need as much info as i can or i just wont be able to tell whats going on in there once i open them up.

I am surprised you ask because all that VM26 carb information is in BikeCliff's website in the GS1000 factory service manual. Going off memory the GS1000 VM26 has #95 Main, Pilot 15, 5DL-36-3 Needle # 3 position, everything else is pressed in and you already know about the air/fuel screws. The owner manual that came with the bike does not tell you anything

 

[chuck hahn]

srsupertrap..i was on the bikecliff site the other day at the library and didnt see anything in the service manual I did find the fork oil requirements and fill amounts and the air pressure settings though..will go back and check again though.

 

[srsupertrap]

No need, I posted this from my service manual which covers the C model. It's like #100 post in the stickey on the top. I just looked at his (Bikecliff's) site and that GS1000 service manual starts with the E model. I didn't mean to be pushy . . . and this may not be exactly correct since this a 79 model.

Suzuki Service Manual: October 1979
GS1000
1979
Model: C

Idle Speed: 900 - 1100 rpm
Carb: Mikuni VM26SS
Id no: 49020
Bore size: 26mm (1.023")
Float height: 24.0mm +/- 1.0 (0.94" +/- 0.04)
Fuel level: 4.0mm +/- 1.0mm (0.16" +/- 0.04)
Air screw: PRE-SET (DO NOT DISTURB)
Cut away: 1.5
Jet needle: 5DL36-3
Pilot Screw: PRE-SET (DO NOT DISTURB)
Pilot Air Jet: 1.2
Pilot Jet: 15
Pilot Outlet: Not specified
Needle Jet: O-2
By-pass: Not specified
Main jet: 95
Main Air Jet 1.5
Throttle Cable Free Play: 1.0 - 1.5mm (0.039"-0.059)

 

[chuck hahn]

I got the same info from there a few miutes ago..at least i will be able to tell if the mains are stock or not. I also read that the needle clip goes on the center slot as well. And as usual with anything else i found it says the fuel and air screws are preset and they dont give any adjustment specs. In the emissions control section it just says that if someone HAS tinkered with the settings seek assistance froma suzuki dealer..WTF!!!

 

[hampshirehog]

Those are the standard carb details for your bike. No probs if someone has fiddled with the adjustment screws - just set them as stated earlier and tweak them till she runs spot on - it's nothing to worry about as it's easy. I bet those punched dimple marks are still in the carb bodies as well - have a look through a magnifying glass if it helps.

 

[Steve]

When the bike left the factory, the pilot fuel screw (the one on the bottom) was probably set between 1/2 and 5/8 turn out from lightly seated. The pilot air screw (the one on the side) was set to some pre-set value to meet EPA standards, which happened to be very lean and make the bike very "cold-blooded". Over the years, we have found that those settings don't work very well in the real world.

It has been hinted above and mis-stated above, but if your bike is stock, as far as airbox and exhaust pipes, the pilot fuel screw probably needs to be between 5/8 and 3/4 turn out. If you have pods and/or a pipe, it will need to be between 3/4 and 1 full turn. As a rule, turn the pilot air screw out twice as far as the fuel screw. When the bike is warmed up, tweak the air screw for highest engine rpm.

When you are done, turn the screws in, counting turns on the way, return them to where they were, record those settings for future reference.

.

 

[chuck hahn]

I am actually hoping that the caps that usually seal the screws are still there..at least if i have to remove them i can turn each carb in till it seats and record the info before disassembly..but as is my usual luck someone will have been in there too!!

 

[hampshirehog]

No caps on the fuel screws on VMs - just a blob of yellow paint.

 

[chuck hahn]

bet its not lined up then..LMAO

 

[BlackStar]

No need, I posted this from my service manual which covers the C model. It's like #100 post in the stickey on the top. I just looked at his (Bikecliff's) site and that GS1000 service manual starts with the E model. I didn't mean to be pushy . . . and this may not be exactly correct since this a 79 model.

Suzuki Service Manual: October 1979
GS1000
1979
Model: C

Idle Speed: 900 - 1100 rpm
Carb: Mikuni VM26SS
Id no: 49020
Bore size: 26mm (1.023")
Float height: 24.0mm +/- 1.0 (0.94" +/- 0.04)
Fuel level: 4.0mm +/- 1.0mm (0.16" +/- 0.04)
Air screw: PRE-SET (DO NOT DISTURB)
Cut away: 1.5
Jet needle: 5DL36-3
Pilot Screw: PRE-SET (DO NOT DISTURB)
Pilot Air Jet: 1.2
Pilot Jet: 15
Pilot Outlet: Not specified
Needle Jet: O-2
By-pass: Not specified
Main jet: 95
Main Air Jet 1.5
Throttle Cable Free Play: 1.0 - 1.5mm (0.039"-0.059)

I just went out to the garage and grabbed my '78 GS1000C factory manual (printed March '78) and confirmed that these numbers are all the same except that the ID# is 49000.