I just bought this factory Honda vacuum gauge set off Ebay.
Not sure why they have adjustable valves on them other than possibly closing off individual gauges for 2 or 3 cylinder engines maybe?
Are the valves really necessary for synchronization of carbs?
All the other sets I seen do not have them.
I believe they are like "chokes" to dampen needle movement.
I have a set of Carbtune gauges and there are little plastic restrictors that they call dampers in the lines so that the gauge doesn't bounce around and is easier to read.
yup. dampening. incidentally, you only need 2 gauges to synch 4 carbs. if you've never done it before, it may not be the way you think it is
do this 1st:
get a few tees, and hook all the gauges up. to where they all connect to one source. then, connect it to a vacuum source, and adjust the valves undil they stop bouncing but show a tiny amount of movement.
look to see if any are reading significantly out from the others. if they are, don't use those individual gauges.
then:
you always synch 1 and 2 to each other, then 3 and 4 to each other. then, you synch the 2 banks to each other. if one of the gauges are defective, you can do this with only 2 gauges.
warm up the bike, then proceed to synch, don't do it cold. im serious, the whole job should take like 10 mins max. snap the throttle lightly a few times, it wont hurt the gauges, and make they they always return back to even.
, get a remote fuel tank if you dont already have one. easy as pie. .
Quote from: m in sc on August 29, 2023, 01:08:55 PMyup. dampening. incidentally, you only need 2 gauges to synch 4 carbs. if you've never done it before, it may not be the way you think it is
do this 1st:
get a few tees, and hook all the gauges up. to where they all connect to one source. then, connect it to a vacuum source, and adjust the valves undil they stop bouncing but show a tiny amount of movement.
look to see if any are reading significantly out from the others. if they are, don't use those individual gauges.
then:
you always synch 1 and 2 to each other, then 3 and 4 to each other. then, you synch the 2 banks to each other. if one of the gauges are defective, you can do this with only 2 gauges.
warm up the bike, then proceed to synch, don't do it cold. im serious, the whole job should take like 10 mins max. snap the throttle lightly a few times, it wont hurt the gauges, and make they they always return back to even.
, get a remote fuel tank if you dont already have one. easy as pie. .
Thanks for that help Mark. Excellent simple explanation.
One thing though, where do you initially set the valves? Further which way do you normally turn the adjuster to calm the needles? In or out?
Again, thanks.
One carb should be a master or not adjustable and you match the remaining, you close off the valves to get gauges to stabilize.
I've seen #2 used a baseline carb because of the typical location of a linked accelerator pump circuit if it has one, but there's no 'master' carb per-say, im my experience with hondas, suzukis, kawasakis and yamaha 4s at least. Not even on old GL1000's.