What carbs do I have?

[speedo1]

O.K., I'm rebuilding my 1000 motor to go into my 750 frame. The motor was complete w/o carbs. I have a rack of carbs, however, I don't know what size. What is stock for the 1000? Also, exactly where do I measure to find out what size carbs. I currently have ( I think they might be from a 750)? Thanks

[KiwiGS]

you measure the carbs where they mount on to the head.
GS cvs will have square tops with a centre circle piece.
CVs will be between 32 and 36 mm
Cheers

[Nessism]

Early GS1000's took 26mm VM carbs - do you have an 8v engine?

[speedo1]

Yes, I'm sorry.. 8V engine, the carbs are VM. If the 1000 came with 26mm, what did the 750 come with? Seems kinda small for a 1000, no?

[Nessism]

750 used 26's are well. A bit small maybe but high velocity never hurts intake tracks.

[speedo1]

O.K., So I'm assuming that the carbs. are off the 750 because most of the parts I got went with this bike. That being said, I guess it doesn't matter what the carbs came on because they are the same, correct? Also, why would they use 26mm on the 750 and 1000?

[dardoonk]

O.K., So I'm assuming that the carbs. are off the 750 because most of the parts I got went with this bike. That being said, I guess it doesn't matter what the carbs came on because they are the same, correct? Also, why would they use 26mm on the 750 and 1000?

Here is jetting for the GS1000S 1979

Carb Type VM26SS
Carb I.D. Number 49010
Bore Size 26
Idle rpm's 900 ~ 1,100 rpm
Float Height 23 ~ 25
Fuel Level 3 ~ 5
Air Screw 1.0
Pilot Air Jet #15
Cut-Away 1.5
Jet Needle 5DL36-3
Needle Jet O-4
Main Air Jet 1.5
Main Jet #95

Here is jetting for the 1978 GS750E

Specs in mm.
Carb Type- Mikuni VM26SS
Carb ID# - 45030
Bore size -26mm
Idle r/min - 1050 +/- 50
Fuel Level - 2.5-3.5
Float Height - 25-27 mm
Main Jet - #100
Main Air Jet - 0.7
Jet Needle - 5F21-3
Needle Jet - O-6
Pilot Jet - #15
Pilot air jet - 1.6
Throttle Cable Play - 0.5-1.0

Note: Main jets, Needle Jets, & Jet Needle are all different. The VM26 will flow enough air to supply the 1000 motor and it will be at a higher velocity (better fuel atomization) than it would be using a larger carb.

Another option would be shell out the money for a set of 29mm smoothbores that use the same rubber manifold as the VM26. Be prepared to pay UP though.

I don't know what is required to adapt a set of 34mm CV carbs to your head.

[KEITH KRAUSE]

If you run "750" jetting on your 1000, it won't run well. If the carbs are from a 750, change every jet to match the 1000. Better to find a set from a 1000. 29 smoothies are the best carb for the 1000 but jetting can be difficult and a good set/parts are getting harder to find.

[speedo1]

O.K., my carbs appear to measure close to 27mm more so than 26mm. Are these still considered 26mm? Also, a carb number of "450" over "50" was seen. I already have these carbs, so, I'll just jet them for the 1000. Stage 3 kit w/ pods the way to go? Thanks!!\\/

[speedo1]

bumpy\\/

[Nessism]

You might want to post some photos of the carbs so we can see what you have. My guess is that you have the stock carbs. Pods with jet kit should take care of the issue I think.

Good luck.