hi. i did a bit of research in internet and found there are many ways to balance the carbs. among those i noticed that the vacuum gauges and fluid manometers are widely used.

1st question - in a 4 vacuum gauge type, does it measure relative pressure to balance the carbs or does it measure the vacuum in each cylinder individually ( not relatively ) ? the reason i asked this is i can't see any relative connection in between the vacuum gauges as we see in fluid manometers. you can see the pictures below



2nd question - can we use a manometer like in the below picture, which measures two carbs at a time to balance all 4 carbs ? let's say first we balance #4 to #3 (master carb). then cap #4 balance adapter and balance #2 to #3. then cap the #3 adapter and balance #1 to #2.



please give some advice. thank you.

 

I have not used the individual gauges before. However,if they're calibrated - they'll work just the same. You have to calibrate the fluid ones too every time you use them. The first step is to connect all four banks to one tube and and put it on one carb to make sure they're reading the same.


While it makes sense that you could in theory use only 2 gauges to do all four carbs because you balance 3&4, then 1&2, and then those two banks to each other - you'll see that 1&2's vacuum draw might change when you're adjusting the middle... So I would advise against it.


I can't recommend the Morgan carbtune enough. I've used it, a motion pro, and a home built fluid type, and it's by far the easiest, and most accurate one. It's worth the extra money if you like carb bikes and plan on doing this more often.

 

thank you very much for your information. to make it more clear i've attached my carb below



since i had bench synced it before this is how it worked. my master carb is #3. balance screw "c" adjusts only the carb #4. balance screw "b" adjusts only the carb #2 and balance screw "a" adjusts only carb #1.

so this is what i did. i made a manometer which measures two carbs at a time.

first i matched $4 to #3
then i matched #2 to #3
after that i matched #1 to #2 ( since #2 already matched to our master carb #3 )

so practically above procedure worked fine. but when i selected a random pair like #1 and #4 and checked them using the same manometer, they were bit out. that's what bothers me now if u can give me some advice it would me much appreciated thank you.

 

I guess that's what I was trying to say, when you go to balance 2 to the master, in theory, everything should stay leveled out, I.e. in sync, but it never does. 1 or 4 will change, and you never know if it's going to draw more or less vacuum - which is why I think it's very important to have the ability to watch all 4 at once. C

 

My 2 cents....
At a macro level, the goal of having balanced carbs is so that 4 mostly independent systems function as 1.
It's much easier and quicker to be able to watch all of them at the same time.

I looked at making my own. While there a certain satisfaction of making something yourself, for me, the time it takes to make a manometer correctly could be spent better elsewhere. But that is just me. Also, my MotionPro guages store ver easy in my toolbox drawer.

But making a set does seem kind of fun.

 

yea you are correct. in theory it should work but practically they change we are measuring the vacuum in our intake manifold i think. so they should be pretty independent. if some one can explain how they relate to each other when vacuum sync it would be much appreciated
and i've seen in lot of Japanese sites they use that vacuum dial gauges which measures vacuum in each carb independently. so just wondering why this tube method which measures 2 carbs at a time is not working 100% to make all 4 vacuum pressures the same. thank you.

actually they are pretty simple i've made both tube and bottle manometers and they worked pretty well. i'm questioning the concept behind these balancing thank you.