Topic: What do you use for vaccume when adjusting carb gauge tool

[strynboen]

better to set the idel to 1500 or 2000 rpm use the tacko..and then set the gauges...no need for a big numbers on the scale..just get it to read the same

[slikwilli420]

The process in sinking the gauges them selves is sort of confusing.
.I was going to set them all to one cylinder with no dampening and get them all the same with full throttle.  then I would dampen them down to the same numbers after they are all the same at full throttle with no dampening.  that makes sense correct?

You are overthinking this by a mile. This is a 40 year old motorcycle, not a complex piece of equipment. Put the gauges on, sync the bike, and go ride.

[Dos]

Yeah but the measurements are off if th gauges aren’t synced

[Dos]

OK I understand I may be overthinking but this is what confuses me when I’m sinking just all four gages to one cylinder I can get them all to the same number at idle however when I open the throttle on one cylinder they show slightly different numbers

Even though this is four gauges into one cylinder!

[flybox1]

just get all the needles to point to the same number, then proceed with a vacuum sync.
you should be done and riding already 

[Deltarider]

OK I understand I may be overthinking but this is what confuses me when I’m sinking just all four gages to one cylinder I can get them all to the same number at idle however when I open the throttle on one cylinder they show slightly different numbers

Even though this is four gauges into one cylinder!

Just don't use one and the same cylinder (working) to 'calibrate' all 4 gauges simultaneously. It won't work. If you did try this, you yourself possibly have messed up the calibration of your gauges... 

[strynboen]

..yes + 10000 on that..take one gauge at time..

[seanbarney41]

Why would you not hook 1 cylinder to a 4 port manifold and adjust all 4 gauges simultaneously?

[strynboen]

think the manifold can give some turbelense in the tubing.

but anyvay.  do it simpel and easy..just hook the gauges on cyll 1..and thange from gauge to gauge.move the rubberline from studs to studs....its the vay i thek..before i do the syncro...dont need any ekstra stuff for that..

[dave500]

with a steady vacuum source hook all four to it,how #$%*ing hard can it be?

[flybox1]

Why would you not hook 1 cylinder to a 4 port manifold and adjust all 4 gauges simultaneously?

A total shot in the dark here.... is that the vacuum from one cylinder, at idle, is already pretty low...now divide that into fourths when simultaneously calibrating gauges.
margin for error goes up with such a small sample of air.
Versus connecting ONE gauge at a time to the chosen carb, you get the full vacuum reading and calibrate to it...

I dunno.....might be talking out my @&&  but ive always done one gauge at a time on one carb.

[madmtnmotors]

Never really thought about calibrating the gauges, but I understand the merit of doing so. My bike runs so much better when synchronized with the gauges as they are that I never gave it much consideration. If I were compelled to calibrate my gauges I would break out the Mityvac and use it as the stable (and measured) vacuum source to do so:

https://www.amazon.com/Mityvac-MV8000-Automotive-Tune-up-Bleeding/dp/B00265M9SS/ref=sr_1_3?s=automotive&ie=UTF8&qid=1534514800&sr=1-3&keywords=mityvac

It's what I use to test automotive vacuum components, bleed brakes, evacuate fluids, etc...

[70CB750]

Why would you not hook 1 cylinder to a 4 port manifold and adjust all 4 gauges simultaneously?

A total shot in the dark here.... is that the vacuum from one cylinder, at idle, is already pretty low...now divide that into fourths when simultaneously calibrating gauges.
margin for error goes up with such a small sample of air.
Versus connecting ONE gauge at a time to the chosen carb, you get the full vacuum reading and calibrate to it...

I dunno.....might be talking out my @&&  but ive always done one gauge at a time on one carb.

I might be wrong, but 4 gauges hooked up to vacuum will show the same value as one gauge hooked to the same vacuum.  I believe Pascal's law applies here.

[Deltarider]

Why would you not hook 1 cylinder to a 4 port manifold and adjust all 4 gauges simultaneously?

A total shot in the dark here.... is that the vacuum from one cylinder, at idle, is already pretty low...now divide that into fourths when simultaneously calibrating gauges.
margin for error goes up with such a small sample of air.
Versus connecting ONE gauge at a time to the chosen carb, you get the full vacuum reading and calibrate to it...

I dunno.....might be talking out my @&&  but ive always done one gauge at a time on one carb.

I might be wrong, but 4 gauges hooked up to vacuum will show the same value as one gauge hooked to the same vacuum.  I believe Pascal's law applies here.

It's mechanical. The dial of the gauge is attached to a ... thing... that changes in size or volume or whatever. So that mechanical 'breathing' or 'pumping' (in reaction to the pulses) in its turn influences the other three. Nothing wrong with a stable common source of vacuum however.

[seanbarney41]

Why would you not hook 1 cylinder to a 4 port manifold and adjust all 4 gauges simultaneously?

A total shot in the dark here.... is that the vacuum from one cylinder, at idle, is already pretty low...now divide that into fourths when simultaneously calibrating gauges.
margin for error goes up with such a small sample of air.
Versus connecting ONE gauge at a time to the chosen carb, you get the full vacuum reading and calibrate to it...

I dunno.....might be talking out my @&&  but ive always done one gauge at a time on one carb.

I might be wrong, but 4 gauges hooked up to vacuum will show the same value as one gauge hooked to the same vacuum.  I believe Pascal's law applies here.

It's mechanical. The dial of the gauge is attached to a ... thing... that changes in size or volume or whatever. So that mechanical 'breathing' or 'pumping' (in reaction to the pulses) in its turn influences the other three. Nothing wrong with a stable source of vacuum however.

that is ridiculous

[TwoTired]

I might be wrong, but 4 gauges hooked up to vacuum will show the same value as one gauge hooked to the same vacuum.  I believe Pascal's law applies here.

You are not wrong.  Besides, even if it did alter the actual vacuum level, it would do it the same to all four gauges hooked to the manifold.  And, the point is to get them all reacting in the same way and the same to whatever vacuum is present in the common manifold.  Then later, when you hook to individual manifold runners, you can adjust them for equal readings with confidence.  It really doesn't matter what the gauge labels say for this to work.  It is the needle position that matters.

Fyi: I use a hand vacuum pump for calibration of all guages hooked to a common manifold.  I think I paid $20 for the pump. I use it far more often to do brake bleeding, though. So it isn't a unitasker.   With the hand pump, you can check the needles at any reading point on the gauge face. And all four at once.

Cheers,

[rotortiller]

Cheap and simple works every time.

[przjohn]

with a steady vacuum source hook all four to it,how #$%*ing hard can it be?

Exactly, like cylinder #1. WTF This is not Rocket Science here folks.

[dave500]

Cheap and simple works every time.

that sucks.

[Deltarider]

Some 30 years ago I was dumb enough to hook up all 4 to one and the same cylinder to 'check' the calibration and at first I was dissappointed to see the differences. However the company that had sold me the set, later demonstrated with a hand vacuum pump that all 4 were actually spot on. So, if you want to check the calibration, use a stable common vacuum pump. That's all. BTW, I haven't used my set in decades. I'm pretty good in doing it on the bench. All three times I managed to have them within 2 cm Hg. What I can, you can too. A vacuum set is ment to shorten labour time in the workshop by not having to remove the carbs. Remember that Honda left the fine synchronisation of new motorcycles to their dealers, that all had a Honda set.

[Airborne 82nd]

Never really thought about calibrating the gauges, but I understand the merit of doing so. My bike runs so much better when synchronized with the gauges as they are that I never gave it much consideration. If I were compelled to calibrate my gauges I would break out the Mityvac and use it as the stable (and measured) vacuum source to do so:

https://www.amazon.com/Mityvac-MV8000-Automotive-Tune-up-Bleeding/dp/B00265M9SS/ref=sr_1_3?s=automotive&ie=UTF8&qid=1534514800&sr=1-3&keywords=mityvac

It's what I use to test automotive vacuum components, bleed brakes, evacuate fluids, etc...

Yes same thing I use. I have had mine 20+ years and it will still hold the reading for hours until I push the release.

[dave500]

same old story,bench sync is ball park,vac sync finalises it,if you came close delta you were lucky,your syncing the vacuum not the actual slides opening gap or what ever anyone calls a bench sync.

[Deltarider]

BTW, I haven't used my set in decades. I'm pretty good in doing it on the bench. All three times I managed to have them within 2 cm Hg.

How did you determine you were within 2cm Hg without a gauge if you haven’t used your gauges in decades? 

How do you think I did? Using a vacuummeter ofcourse, how else could you do it? 

[rotortiller]

that sucks.

And it does so very well! 

[Dos]

Well #$%*.. I didn’t know this would blow up haha.. so am I back up square one!?

I have improperly synced my gauges!?

Or I have synced with one cylinder into 4 gauges!?