1978 gs 1000 e sputters at 3/4 to full throttle

[chuck hahn]

Use the baseline settings for the pilot and mixture screws. As you can see by my signature, I have GS 1000s and I know where mine are liking things. Here is what I have found to work on the VM carbs..which yours should have.

PILOT SCREWS ( BOTTOM ONES BY THE BOWLS ) 7/8 OUT And you LEAVE THEN ALONE after setting them!!!!!!!!!!!!!! HANDS OFF!!!!!

MIXTURE SCREWS ( ON THE SIDE OF THE CARB THROATS ) 2 OUT AS THE START POINT. Then you do ALL of the FINE TUNING from the mixture screws...period. Turning the mixture screws IN will RICHEN the mixture. OUT will LEAN the mixture. Make all adjustments NO MORE THAN 1/8 turn at a time and give the engine a few seconds to reequalise itself after making adjustments.

[chuck hahn]

And the sync can be affecting the response as well.

[rudeman]

And the sync can be affecting the response as well.

More so off idle than at 1/2 to WFO.

Good advice from Chuck re: fine tuning the mixture using ONLY the mixture screws. FYI: The pilot screws on my EN were set at 3/4 out. There is some slight variation on that setting apparently. Record your current settings before changing them, especially if the bike is running.

The process is not easy but it is rewarding when you get her dialed in. Enjoy it and learn from it.

[chuck hahn]

Rudeman..the 3/4 was the factory setting far as any information I have ever been able to gleen. This, however, was at the very edge of being TOO lean because of the 70s EPA bullcrap back then.

The 7/8 is just a slight slight bit richer.but not too rich from what I have been able to tell from how mine react. And my feeling is that I would rather be just a tad richer than too lean for the health of the valve train!!

[Spyderman]

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)

1978 GS1000 (VM carbs)



Pilot Air Jet: 1.2
Pilot Jet : #15
Cut-a-Way: 1.5
Jet Needle: 5DL36-3
Needle Jet: O-2
Main Air Jet: 1.5
Main Jet: #95
Float Height: 23-25mm
Fuel Level: 3-5mm


here are your stock factory carb settings
for the pilot circuit follow what chuck hahn has outlined for the pilot screws and the mixture screws



these carbs have 3 circuits to then
Pilot circuit = 0 to 1/4 throttle
needle jet and jet needle = 1/4 to 3/4 throttle
main jet = 3/4 to wide open throttle

it would seem to me that perhaps you are having a problem with the main jet circuit by what you are describing
i would take the carbs apart confirm that they are clean and check all your settings and jet sizes if they are all correct

then perhaps it is a fuel starvation problem at that throttle setting.
i had this issue with my 78 1000 the petcock was suppling enough fuel but the smaller fuel line and low flow fuel filter was causing fuel starvation at above 3/4 throttle the solution was slightly larger fuel line and a high flow fuel filter
i use a 95 CBR 900 RR fuel filter on my bike emgo part # 14-34481
i had 3/8 fuel line on it and i now have 7/16 fuel line and when i made this change i had no more problem with it cutting out above 3/4 throttle

[lrgguy]

Thank you all !!!today I got a little free time . Installed the new front break pads and the new air filter .. due to more work in the am didnt yank the carbs to throw in my 4 new #95 main jets . All my pilot jets are 15's btw .. why the previous owner had 3 - 102.5 main jets and 1 - 95 main jet makes no sence .. oh through in 4 new spark plugs tonite too .. noticed the bike was running a little better after new plugs ... work crazy hrs again sunday through to friday so maybe next weekend will have some more free times to yank the carbs again ..