78 750 Carbs: Where are my air screws?

[TiberiusM]

So here are my carbs off my 78 GS 750(EC) They're VM26SS'

I'm lead to believe there should be a vacuum port on carb#3 but it doesnt look like its there, but thats not why I'm here




My airscrews...aren't there? I've heard people say there are plugs on some CV fuel/pilot screws, but those don't look like plugs. So uh...what do I do? Just ignore it and try to sync as is?

As an aside, its also currently jetted very oddly. Its got pods and a 4into1 header and is running 17.5 pilots and 115 mains. And the needle was clipped at the 3rd slot in 3 of the carbs, and the 4th slot on the last carb (came from the PO like this, so who knows what he was trying to do). I ordered some 125 mains and shifted the clip to the 4th slot on the needle according to a few threads I found from a while ago. Even with a good cleaning, new needle position, and fuel screw positions its already running much better, just gotta put the new main jets in, do a valve adjustment on it, and sync, then I'll be ready to fiddle with jets some more. But the whole airscrew thing confuses me.

Oh, and since I'm missing a vacuum port, is it feasible to pull a vacuum from one of the balance ports on the manifold? I've currently got the ability to rig it that way, but I'm not sure if it'll work or not and didn't know if it was a bad idea or not. Its either that or convert my petcock to a manual, which would probably be better in the long run.

[Tarbash 27]

I dont think those are the original carbs, the original carbs should only have one fuel inlet, and it should be between the center carbs. You may have a set of kawi carbs. There are no air screws on this set. The screws would be right on the intake side of he carbs, angled away from the carburetor. It should be where you have a little brass dot .

[Nessism]

The fuel feed is supposed to be one tube between carbs 2-3, your carbs have two feeds. Those plugged air screws are strange too. I wonder if those could be Kawasaki spec VM's? Not sure what to suggest other than maybe looking for a different set. Lots of different GS models use the VM26's so it shouldn't be too hard to find a rebuildable set if you decide to switch.

Edit: Trashbar posted while I was typing. Great minds think alike.

[TiberiusM]

I figured something wasn't original, as I have a vacuum petcock but no vacuum port. Wasn't sure which, but now I know. Thanks!

I checked some prices on ebay, and new(used) carbs are a bit out of my range at the moment, so I'll probably just stick with these and work around them.

Would not having airscrews be a big deal? Would it just make tuning a bit more of a hassle or do I really need them?

[Nessism]

I'd say no big deal. Tweak the fuel screws to change the mixture...just make the fuel screws have a sharp pointy tip and the hole in the carb body isn't butchered (the fuel screws love to break off inside the carb body).

[TiberiusM]

ok. Fuel screws looked good. Sharp and pointy, with a good hole through the carb. One screw does seat a bit lower than the rest, but its easy enough to get close/ready to tune.

Thanks for the info. Its nice knowing I don't have some freak carbs by accident. The whole bike seems to be an amalgamation of parts. According to the engine number its a 78 750 EC, but its got spoke rims with single disc brakes. So either they were still being made that way in 78, or things have been changed around on it. I don't have any good pics of it, or I'd link them.

Anyway, thanks again for the help.