No vacuum gs 750 1978

[simonk]

Hello big brains, a friend has just bought a 78 gs 750, he was having some issues so he gave me a shout, because I have a thou. So I have been looking at the carbs, the are VM 29s they are different to my 1000 carbs, in that 1 and 3 are blanked off where the vacuum pipe would be for the petrol tap. Is that normal..the mixture screws underneath appear to be blanked off..is that normal..it has a lot of non standard stuff.braced swinging arm, blue box ignition etc so I cant be sure what's right..or original, as I have no history.the air screws on top were barely a quarter turn out. And the plugs are black..it is smokey on start up so I figure bad valve seals. So do I drill out the mixture screw caps...? And is that a standard set up on the vacuum side of things. Or should it be more like my thou. Thanks in advance for any information.

[Rich82GS750TZ]

Welcome. Best place to start is probably for your friend to start their own membership here, unless you’re planning on being the go-between with all the info.

Top 10 Newbie mistakes, linked in my signature. I didn’t write it, but everyone should read it.

BikeCliffs Website, linked in my signature also, has, owner’s and factory service manuals, and wiring diagrams in the top section that both you and your friend need. Bookmark that site. Great carb tutorials on cleaning/rebuilding VM and CV carbs a little lower down in the right side columns. Lots of other tutorials on that site that you both need.

Salisbury, what state or country? Some bikes had different spec in different locations. It will help you get the right info.

[allojohn]

Stock carbs are VM26's on the 750's. Sounds like it's running way too rich, maybe because of the oversized carbs...

[simonk]

Thank you..so the carbs are wrong..and on the 750 vacuum on 3 yes?

[allojohn]

Yes, vacuum on 3.

[Rich82GS750TZ]