Author Topic: Carb venting  (Read 1309 times)

0 Members and 1 Guest are viewing this topic.

Offline Boy named Suzi

  • Full Member
  • *
  • Posts: 18
Carb venting
« on: August 19, 2009, 08:28:54 PM »
....so....
  Have a '77 GS 750, have rebuilt the carbs and am looking for advise on how to vent the stubs. It has 4 carbs, 1 actuates the vacuum petcock and the 3 others are to be routed. The vents are also connected in pairs (2 each side of throttle linkage). Do the remaining stubs get ganged together to share/modulate inlet vacuum (this setup is how the bike arrived - non operational!), or as also suggegted, do the sit open and suck air? Why have hose stubs then?

Any advise appreciated, I know it's not 'technically' a SOHC, actually not a SOHC at all. It does qualify as an other, yea!
thom
Thom

Offline crazypj

  • I'm brill, me
  • Old Timer
  • ******
  • Posts: 4,467
  • first 100,000 miles. 1977 CB550F
Re: Carb venting
« Reply #1 on: August 19, 2009, 08:48:58 PM »
except for the vacuum line, the others should have rubber caps. Don't leave them open, runs real lean and will cause damage.

PJ
I fake being smart pretty good
'you can take my word for it or argue until you find out I'm right'

Offline Dawdlin Dog

  • Enthusiast
  • **
  • Posts: 145
Re: Carb venting
« Reply #2 on: August 20, 2009, 04:24:04 AM »
Don't know whether your carbs are the same as the 850 but this page helped me solve a problem I was having with my GS  http://members.dslextreme.com/users/storagecliff/images/hose_locations.html
My bike can be repaired.
My insanity is a little more permanent.

Offline kirkn

  • Expert
  • ****
  • Posts: 1,046
Re: Carb venting
« Reply #3 on: August 20, 2009, 09:39:36 AM »
except for the vacuum line, the others should have rubber caps. Don't leave them open, runs real lean and will cause damage.

PJ

+1

one port runs the vacuum petcock.  other 3 get capped.  Except during carb synchronizing, when theoretically, you're using a temporary fuel set up and using all four ports for sync-ing.


Offline Boy named Suzi

  • Full Member
  • *
  • Posts: 18
Re: Carb venting
« Reply #4 on: August 21, 2009, 09:26:01 AM »

  Thanks all! Gonna try with long hoses. The manual shows hoses, and in the manuals pictures but no routing.

  Thanks Kirkin, was going to undo plugs in the intake manifold, these stubs are a more logical (it's about a bike so I don't use logic, much) place to connect the guages. Thats a job for the winter...

  Running right this weekend? Hope so!
Thom