Carb Bench Sync'ing.... Noob Question

During the course of my benching tonight, I noticed that the Vacuum on #3 increased after I balanced 1 and 2 together. I had around 8 on the gauge when I first started then when I came back to it, it was around 14.

Is that normal?

And which way do you turn the screws to increase and decrease your vacuum??

 

Normal.

Bringing in One and Two made the Carbs Idle more effeciently and probably introduced more air.

More air ... more fuel. Faster Idle.

Faster Idle : More Vacuum.

Reduce the Idle by making an adjustment to the Idle Adjustment Rod located beneath the Carbs, in the middle, between two and three.

 

ok... so now to double check.

Which way would I turn the screws on 1, 2, and 4 to increase vacuum?? In or Out?

 

your final adjustment should be to bring 2 to 3, move the screw slightly in either direction and watch the guage.

 

I understand that, but I am just trying to double check before my final adjustment.



Which way would I turn the screws on 1, 2, and 4 to increase vacuum?? In or Out?

 

I can never remember which way to turn the screws, even after only 2 minutes!

If you turn the screw and the needle goes the wrong way just turn it the other direction.

 

Well, what worries me is that have after half a turn in either direction, I am not seeing much of a vacuum change and I have no vacuum leaks.

 

You are leaving the vacuum gauge on #3 ?

If you are adjusting other carbs, and reading #3, you are doing it wrong.

 

No, I am not leaving the gauge on #3.

I have the gauge on #4 and adjusting the screw designated for #4.

 

I just synchronized my carbs this weekend and noticed the same increase to the vacuum across all 4 gauges, once they where in sync. I also notice a slight increase in the RPM, so I agree with RickCo, once the carbs where in sync the motor ran much smother and picked up RMP. Using the idle adjustment screw returned the idle to 1050 RMP and noticed a drop in vacuum reading.

 

well.. I finally got it and I have to say that you definitely need two vacuum gauges in order to balance the carbs out.

 

No you don't need two.
You can put all four of them dead-on with one.

I have done it dozens and dozens of times!
With perfect results!!!

 

I know you can but it is definitely easier with two as you don't have to keep switch between the carbs to get them to measure up.

 

you can get some aquarium valves at a pet store or walmart, then all you have to do is flip the valves
much faster so you can keep track of what your doing

 

With four hoses connected to the Manifolds extending out to the left hand side of the bike ... held in-order by a aftermarket Spark Plug Loom connection ... so as not to get them confused ... you can get pretty good getting the values between the 3 Carb and the one you are working on.

With a quick thumb and a couple of golf tees in-between your lips ... the process gets to be pretty easy after you get settled in and get the Idle right.

I got tired of doing it the Old School Way and broke-down and bought a set of Mercury Carb Sticks from MotionPro.

But, I think I could let someone who never synced Carbs before use the Mercury Sticks and I'll use my old Vacuum Gauge and be done bringing-in the sync about the time the new guy gets it all figured-out!

Either way, it's fun to get to the Vacuum stage of syncing because you know you are getting close to having your bike all tuned-up real nice.

It gets to be a joy after awhile, particularly if the person needing the sync is the grateful kind of client and is a big tipper.
Nothing makes a person happier than leaving on a tuned-up ride and not having spent a fortune getting the tune-up!

Tuned-up is fun.
You get to enjoy riding the bike and almost forget about the process that went inn to getting there after you start getting lost playing with the throttle and having the bike respond like a winner!