TB balancing gauges

[DanPez]

There is lots of talk about TB balancing and I was wondering what type of balancing gauge would you recommend for TB adjustments.
1) TwinMax?
2) Carb Stick?
3) Home made water column?
The simplest and less expensive would naturally be the home made one .... but would you fill it with water, oil for damping?

Also ....has anyone measured the vacuum value from the TBs? ..... By this I mean "vacuum from the throttle nipple connection with respect to atmosphere".
What I do have is a vacuum indicator where I was able to get the following ...... at idle 17 cm hg of vacuum on both TBs jumping to 19cm hg of vacuum on both TBs.
At 3000 rpm I had 23 cm hg of vacuum on both TBs and they seem balanced at +/- 1cm hg.
(These values are the actual values I measured from my 09 Stelvio)
If so ..... is there an adjustment for this?

The reason I'm asking this is because of the ECU being a MAP ..... this value can determine the air volume at different RPM.

Thanks

 

[john zibell]

Dan,

My preference is Carb Sticks http://pitposse.com/moprosyproca.html you can't get the mercury ones any more. Some swear by the twinmax, but to me, columns of liquid can't lie. Also within 1cm is a terrible balance. With the sticks, you can get the TBs dead on. Only rawback with the sticks is they are not very portable like the twinmax.

 

[DanPez]

Dan,

My preference is Carb Sticks http://pitposse.com/moprosyproca.html you can't get the mercury ones any more. Some swear by the twinmax, but to me, columns of liquid can't lie. Also within 1cm is a terrible balance. With the sticks, you can get the TBs dead on. Only rawback with the sticks is they are not very portable like the twinmax.

John,
This model has an individual column zeroing for what I can see.(Which is good)

I tried to see up close a picture of this gauge ......what is the precision? (Smallest increment reading)

 

[Spaceclam]

I vote for the homemade device. I used 30 feet of 1/4" clear vinyl tubing, and filled it with ATF, cause it's red, and it's mostly detergent, if some gets sucked up. Just use the banjos from the carbon canister, then tape the loop of tubing to a ruler or something. Cost me about $4.

-Clam

 

[DanPez]

I vote for the homemade device. I used 30 feet of 1/4" clear vinyl tubing, and filled it with ATF, cause it's red, and it's mostly detergent, if some gets sucked up. Just use the banjos from the carbon canister, then tape the loop of tubing to a ruler or something. Cost me about $4.
-Clam

Clam,

I agree with you this is the cheapest way to sync the TB's ...... what I'm looking for is also accuracy.
With a U tube you can get it balanced properly but what is the really vacuum value from each TBs? :?:

What I mean is if you fill the tube with ATF ..... you would get a different precision than filled with water.

 

[GuzziMoto]

I vote for the homemade device. I used 30 feet of 1/4" clear vinyl tubing, and filled it with ATF, cause it's red, and it's mostly detergent, if some gets sucked up. Just use the banjos from the carbon canister, then tape the loop of tubing to a ruler or something. Cost me about $4.
-Clam

Clam,

I agree with you this is the cheapest way to sync the TB's ...... what I'm looking for is also accuracy.
With a U tube you can get it balanced properly but what is the really vacuum value from each TBs? :?:

What I mean is if you fill the tube with ATF ..... you would get a different precision than filled with water.

It is not so much about what the reading is but that both sides read the same. Balanced.
I like the twin max idea, but a home made device should work just fine. The atf is less harmful then water if it gets sucked in to your motor and being red it is easier to see the levels. You could use any light oil, it does not have to be atf. I have an old set of mercury sticks around somewhere. My friend has a home made version of the same.

 

[Brian UK]

As stated above, the actual value is meaningless, all that matters is that both sides are the same. In this respect, the U tube manometer is by far the most accurate, and can never go wrong. Mine is filled with ATF too. Of course it's not portable really, but you don't normally need to take it with you.

 

[DanPez]

As stated above, the actual value is meaningless, all that matters is that both sides are the same.

Brian,

This is where I would disagree with you ...... when you say the actual value is meaningless.
It's true I am looking for a gauge to balance the TBs checking to see if they are in sync but at the same time what if I want to verify the vacuum value with respect to the throttle body angle or rpm?
Example ..... I decide to upgrade the airfilter ..... I just changed the vacuum value.
Wouldn't you agree :?:

The carb sticks that John recommended seem to be the ticket ..... but do not know if there is a scale value.
The idea is at this moment I know that the bike is running really well ..... I would like to keep this information handy for the next maintenance. (I tend to overkill) :S :silly: :blink: :woohoo: inch:

 

[GuzziMoto]

As stated above, the actual value is meaningless, all that matters is that both sides are the same.

Brian,

This is where I would disagree with you ...... when you say the actual value is meaningless.
It's true I am looking for a gauge to balance the TBs checking to see if they are in sync but at the same time what if I want to verify the vacuum value with respect to the throttle body angle or rpm?
Example ..... I decide to upgrade the airfilter ..... I just changed the vacuum value.
Wouldn't you agree :?:

The carb sticks that John recommended seem to be the ticket ..... but do not know if there is a scale value.
The idea is at this moment I know that the bike is running really well ..... I would like to keep this information handy for the next maintenance. (I tend to overkill) :S :silly: :blink: :woohoo: inch:

No, changing to a free'r flowing air filter will have little if any impact on the vacuum value. The vacuum is mainly a factor of engine rpm and throttle angle. The reading is taken between the intake valve and the throttle body. Changes on the other side of the throttle body will have little impact. It does not matter that the air filter will flow more air into the engine when the limiting factor is the throttle body. Until the throttle is opened substantially there is not going to be much change in vacuum or in the amount of air going into the motor.
The vacuum is a product of how much air the motor is trying to suck in versus the restriction in the intake port that the throttle body is when closed. Meaning, when the throttle is closed the motor is trying to suck in more air then the throttle butterfly will let it. That is where the vacuum mainly comes from. That value will change with rpm and air/fuel mixture.

 

[john zibell]

Dan,

My preference is Carb Sticks http://pitposse.com/moprosyproca.html you can't get the mercury ones any more. Some swear by the twinmax, but to me, columns of liquid can't lie. Also within 1cm is a terrible balance. With the sticks, you can get the TBs dead on. Only rawback with the sticks is they are not very portable like the twinmax.

John,
This model has an individual column zeroing for what I can see.(Which is good)

I tried to see up close a picture of this gauge ......what is the precision? (Smallest increment reading)

Doesn't matter what the increments, marks, on the back side of the tubes are, get them dead even and you are good.

 

[DanPez]

No, changing to a free'r flowing air filter will have little if any impact on the vacuum value.

I agree very little effect …. depends on how you look at it

The vacuum is mainly a factor of engine rpm and throttle angle.

I agree to have a reaction in RPM the throttle angle has to change ….. change in TB angle leads to RPM change.

The reading is taken between the intake valve and the throttle body. Changes on the other side of the throttle body will have little impact. It does not matter that the air filter will flow more air into the engine when the limiting factor is the throttle body.
Until the throttle is opened substantially there is not going to be much change in vacuum or in the amount of air going into the motor.

What I did was measured vacuum values with a precision indicator (Used in the industries) and what I actually have is...... at idle 17 cm hg of vacuum on both TBs jumping to 19cm hg of vacuum. At 3000 rpm I had 23 cm hg of vacuum on both TBs. Example when the TBs are opened at 4.7 deg it idle ……5.3 deg for a steady 2000rpm ……. 17.6 deg for 4000rpm …… these are my VDST log values. I found that I didn't have to open the TBs a lot for the rpm obtained. (Max TB 82 deg)

The vacuum is a product of how much air the motor is trying to suck in versus the restriction in the intake port that the throttle body is when closed. Meaning, when the throttle is closed the motor is trying to suck in more air then the throttle butterfly will let it.

This is where I would say if you have open air …..or at the other extremity blocked air filter it changes the vacuum value


I did find something to sync the TBs and used for diagnostic purposes also...... "Vacuummate"?
Found it at http://www.vacuummate.com/
I would have to see if someone in this forum ever used one .....and their opinion on the product?

 

[john zibell]

I did find something to sync the TBs and used for diagnostic purposes also...... "Vacuummate"?
Found it at http://www.vacuummate.com/
I would have to see if someone in this forum ever used one .....and their opinion on the product?

What will really tell how good it is is to balance with the Vacuumate then compare results against carb sticks. Since it is electronic, we don't know the sensitivity, and to me columns of a liquid is the gold standard.

 

[GuzziMoto]

The vacuum is a product of how much air the motor is trying to suck in versus the restriction in the intake port that the throttle body is when closed. Meaning, when the throttle is closed the motor is trying to suck in more air then the throttle butterfly will let it.

This is where I would say if you have open air …..or at the other extremity blocked air filter it changes the vacuum value

Unless your air filter was so clogged that it could not flow enough air to meet the intake air needs of the motor at or just above idle (that would be seriously clogged) then no, the air filter is not the limiting factor on how much air is going into the motor. So changing it is not going to effect how much air goes into the motor at or just above idle. Until you open the throttle far enough that the air filter becomes the limiting factor in how much air goes into the motor changing the filter should not have a noticeable effect on vacuum. Unless your filter is seriously clogged this will not happen until at or near full throttle.

There are many electronic devices to help you balance the throttle bodies. As mentioned, the gold standard are carb sticks. An electronic device would do well to match carb sticks and would be hard pressed to beat them for accuracy. I see no reason to bother with something that costs more money and will likely be no better. If you want to give it a go, let me know how it works. But as mentioned already, you are worrying too much about the exact number when all that matters is that they are even. Balanced.

 

[mwest]

Unless you're willing to have the vacuummate calibrated on a regular basis, I wouldn't count on it giving you absolute values. Personally I don't trust electronic ones. There is inaccuracy added in converting the vacuum pressure to electrical signal and then you have software that has to convert that signal to what is displayed. With the pulsating vacuum from a motor, there is likely some averaging going on and you don't know how that affects your reading or if it affects it differently at different RPM's.

I use the Morgan carbtune. Same principal as carb stix but without liquid it does have vacuum readings but I don't know how accurate they are nor care since balancing is all I'm concerned about. Since it could go out of sync, I check it regularly by swapping hoses and ensuring the readings match.

I do agree with others that liquid is the gold standard.

 

[GuzziMoto]

Unless you're willing to have the vacuummate calibrated on a regular basis, I wouldn't count on it giving you absolute values. Personally I don't trust electronic ones. There is inaccuracy added in converting the vacuum pressure to electrical signal and then you have software that has to convert that signal to what is displayed. With the pulsating vacuum from a motor, there is likely some averaging going on and you don't know how that affects your reading or if it affects it differently at different RPM's.

I use the Morgan carbtune. Same principal as carb stix but without liquid it does have vacuum readings but I don't know how accurate they are nor care since balancing is all I'm concerned about. Since it could go out of sync, I check it regularly by swapping hoses and ensuring the readings match.

I do agree with others that liquid is the gold standard.

There is also the question of resolution with some of the electronic devices. The one in the link, for example, has LED's that work in steps so there is a limit to its resolution. Like a bar graph tach.

 

[DanPez]

I use the Morgan carbtune. Same principal as carb stix but without liquid it does have vacuum readings but I don't know how accurate they are nor care since balancing is all I'm concerned about. Since it could go out of sync, I check it regularly by swapping hoses and ensuring the readings match.
I do agree with others that liquid is the gold standard.

The Morgan Carbtune is scaled 10 to 42 cm hg ...... what I mean is that it has a reference value ......with each line capable of measuring 0.5cm hg. (The adjustment of balancing is as accurate as the "Vacuummate") and $400 less
And the reading is metal tubes (damping)...... and has separate vacuum readings (Unlike U tube differential reading) :woohoo: :woohoo:
The search for gauges is getting better all the time :!:

 

[double.d]

I bought a Carbmate device, lots of red, green and amber lights going off, but when it comes down to it there is just the finest adjustment between the red green and amber that if you are one colour out it's not going to make any difference, it's just the end 2 cylinders cut of a V8 that you are trying to make perfect :roll: and it will never be perfect cause there are too many other variavbles that will effect perfection :arrow:

 

[Penis Rotor]

I bought a Carbmate device, lots of red, green and amber lights going off, but when it comes down to it there is just the finest adjustment between the red green and amber that if you are one colour out it's not going to make any difference, it's just the end 2 cylinders cut of a V8 that you are trying to make perfect :roll: and it will never be perfect cause there are too many other variavbles that will effect perfection :arrow:

:idea: :arrow: Give the man a cigar! :mrgreen:

It's a ditchpump fer crying out loud.

Pete

 

[DanPez]

Update on the gauge……
When I had the Stelvio’s maintenance done ...the mechanic that checked the TB sync told me that he uses a Twin Max as a measuring device for balancing.
The difference from when I brought it to the shop and got it back was great ….. I felt that it was running smoother especially from idle to 4000 rpm.

This is why I asked your opinion on what gauges you use to balance the TBs.

I rechecked the TBs with a graduated (inch) U-tube filled with ATF ….. as Clam recommended….. found it to be cheap and ATF being liquid "columns of liquid can't lie" John's quote.



I went a little further just to calculate the precision …… SG of water compared to ATF.....so I had time to waste. :blink:

I connected the U-tube to the TBs (engine hot) at 3000rpm I was off by 18”….9" on one side and 9" on the other(2.7cm hg).
I readjusted the TBs with the procedure we have here, on the forum, and was able to get +2” at idle and -2” at 3000rpm. (U-tube shifts side) +/- 0.3cm hg.

All I can say is what a difference!!!!!! :woohoo:

A ditchpump? .........an expensive ditchpump!

 

[Rafael]

I have a set of the old mercury Carb stix, MotionPro SyncPro, and the Carbmate by Tecmate. The carbstix are hanging on the garage wall for decoration now, but still work after 25+ years. I tuned the Breva with the SyncPros then the Carbmate about a month later. I was able to get the TBs balanced more closely with the Carbmate and the improvement was noticeable. The process is quicker with the Carbmate as well; don't have to hang'm too.

One observation I've made that contradicts my understanding of the air bypass is that the idle balancing does seem to affect the balance and 3k rpm balance a bit.

I connected the Carbmate to a spare battery to avoid removing the battery cover then connected the VDSTS to the same... big mistake. The VDSTS has to connected to the bike battery. Instructions, who needs them? :whistle: