Topic: Vacuum Sync 7A Carbs CB750K1

[pjandrew99]

All of my carbs are adjustable versus carb 2 being non-adjustable and setting them all to carb 2.
That being the case, do I just try to set them all the same or is there a procedure to use when all carbs can be adjusted?
Thanks

[Rookster]

They are all adjustable.  You choose which carb to make not adjustable.  Before you choose which carb to tighten down and make non adjustable make sure there is at least 1 thread showing above the top nut.  There is a spec for this in the workshop manual but 1 thread covers it.  Then you make changes to the other 3 carbs.  Make sure the engine is warm and rev it a little bit after each change to see where they all settle at.  It's common for 1 adjustment to affect all the carbs.  If you are using gauges with liquid then reving the engine will cause the liquid to escape.  It might take you a few tries before you get the hang of it.

Scott

[Scootch]

What sync tool are you using? The manual says to set the free play at the top of the carbs. Set the idle mix screw for the carbs you have. On my K0 that's 1 turn out from seated. Then I make sure I adjust the idle stop screw so that all carbs are opening and closing the same in sync. I do this with the motor off, roll the throttle grip open a quarter turn or so then roll the throttle closed and listen to when the slides close and hit the stop screw. If all slides don't hit simultaneously I adjust the carb that is off using the stop screw. When they are all dropping the same I fire up. At around 1500 RPM the manual says you should be pulling around 20-22 cm/Hg. Adjust each carb to get 20-22 using the stop screw. Make sure you don't have vacuum leak at the carb ports - or anywhere else. I use a carbtune syncher.

[pjandrew99]

Thanks guys.
I use the carbtune as well. Great info. Much appreciated!