carbtune vs beer bottles

[gearman]

I apolagise for the pictures but the thumb nails are so small I cant see what I am putting up. I had 12cm hg with the carbtune on the trike, but only 8 or less on the two wheeler at the same rpm.Wth?The bottles are more sensitive.

[Cdn850T5NT]

Is there another thread on Wild Guzzi that explains the beer bottle buildup, operation?  I generally can see it but would like a bit more info... Cant see the top loop fully, e.g.

[Joliet Jim]

I've never seen the beer bottle. I always used the yardstick, hose, and trans fluid to balance

[Kiwi_Roy]

The tube over the top acts as a syphon to move fluid from the side with lesser vacuum (higher absolute pressure) to the side with stronger vacuum (less absolute pressure), at some point where the carbs are almost balanced the transfer of liquid will stop and the relative vacuum will be indicated by the liquid height.
I imagine unlike a simple "U" tube manometer it is quite well damped as the inside diameter of the bottles is many times greater than that of the syphon.
It's very clever really 

[John Warner]

Is there another thread on Wild Guzzi that explains the beer bottle buildup, operation? 

Obviously we only need two, but this shows the idea fairly well.
There are other on YT, just search 'DIY Carb Balancer'

https://www.youtube.com/watch?v=0HfrHLmpHCY

[80CX100]

I've never seen the beer bottle. I always used the yardstick, hose, and trans fluid to balance

Same here

[Cdn850T5NT]

Obviously we only need two, but this shows the idea fairly well.
There are other on YT, just search 'DIY Carb Balancer'

https://www.youtube.com/watch?v=0HfrHLmpHCY

Thx.

[Wayne Orwig]

I apolagise for the pictures but the thumb nails are so small I cant see what I am putting up. I had 12cm hg with the carbtune on the trike, but only 8 or less on the two wheeler at the same rpm.Wth?The bottles are more sensitive.

Are you meaning mercury compared to mercury?

Valve clearance. Cam profile. Obviously vacuum leak. Ignition timing might (not sure on that).

[Rough Edge racing]

 I prefer this tool, it measures air flow not the MAP downstream of the slide or throttle plate...No hoses, no liquid, but may not fit into position on a Guzzi without a home made adapter...

         

[gearman]

Are you meaning mercury compared to mercury?

Valve clearance. Cam profile. Obviously vacuum leak. Ignition timing might (not sure on that).

Yes both on Carbtune which uses metal rods  and springs.What does a stock convert measure in cm/hg?

[Cdn850T5NT]

The tube over the top acts as a syphon to move fluid from the side with lesser vacuum (higher absolute pressure) to the side with stronger vacuum (less absolute pressure), at some point where the carbs are almost balanced the transfer of liquid will stop and the relative vacuum will be indicated by the liquid height.
I imagine unlike a simple "U" tube manometer it is quite well damped as the inside diameter of the bottles is many times greater than that of the syphon.
It's very clever really 

I've a question:  to the extent that there will always be a head of fluid in the fluid transfer line of the bottle which is transfering fluid to the other bottle - does this mean that strictly, the difference in heights of fluid in the respective bottles (as a mimic of the absolute pressure differences. one cylinder to the other) is not 100% accurate on account of this liquid head?

Now, does it make sense to NOT have really tall bottles, or to make the loop tall, so as to minimize this effect?  What if you used, say, two 500 ml (roughly 1/2 quart) Mason Jars... and made the crossover tube as low-profile as possible?  Now the resolution likely will go down... if the diameter of the vessle / bottle / jar is large.... versus small diameter, I would guess.

Also, it appears that there are two critical elements... i) that the bottles be really solidly fixed down onto the wooden base (lest they fall over); and ii) you start by adding fluid to only one jar / bottle... say to 3/4's full or 7/8's full.  Then you blow into one of the hoses to equalize to the other bottle.  That way, if ALL of the fluid transfers to the other side... it still has "freeboard"  and will not allow water or water/glycol to be drawn into the engine.  'Real important!

Others... people better at physics than I - please offer your comments!

[Kiwi_Roy]

I've a question:  to the extent that there will always be a head of fluid in the fluid transfer line of the bottle which is transfering fluid to the other bottle -

No, the head of fluid over the top is balanced so its effect is effectively zero, In fact if you were to drill a hole through the glass at the bottoms of the bottle and connect them there it would be the same, the beauty of using the top inverted "U" tube, it saves you having to drill a hole through the glass and seal it. If you were to disconnect the bottles from the bike when one was 3'' higher as long as the syphon was filled the level would slowly come back to the same on both sides.
If the diameter of the vessels was larger it would effectively damp the gauge, it would come to the same levels just take longer.
Manometers are neat devices, you can measure very accurately with them, they are used as a standard by which other gauges are compared.
Yes you are right, the total contents must fit in one jar otherwise there is the possibility of sucking fluid into the engine.
I use just a normal U tube about 3 ft high only I use engine oil, this provides some damping and would burn harmlessly if sucked into the motor albeit with a lot of smoke.
Many manometers have a cork near the top, if the fluid rises up it floats and plugs a valve similar to the float valve in a carb.
Another simple instrument you might find interesting is a Hook Gauge, they can measure extremely low pressures.
I used to teach plant operators to accurately measure low pressure with a length tube and a bottle of water.

[Cdn850T5NT]

What you are saying, Roy, is that the transfer tube is filled on both sides... and that is why it does not impact matters (re measurement).  I should have figured that out... that is how you siphon liquids....  DUH!  Brain fa*t.

Cheers!

[Cdn850T5NT]

I get the impression this is very accurate and hard to set the carbs so they are both at same liquid level. I have mercury containing columns... forget the make.(Motion-Pro?).. but i actually can get bubbles of gasoline condensate in the columns... that ha9s to be purged out with an air containing syringe.  I do like the columns though because i can easily adjust throttle cable take-up... seeing immediately which cylinder has less slack in the cable. This water glycol based system does take a moment to react and change level, i would guess...?

[John Warner]

The levels are unimportant, the idea is that you're looking for movement in the levels, between one Bottle and the other.
Zero movement equals perfect balance (equal Vacuum in both Inlets).
I'm pretty sure the Carbtune with the Metal Rods has no Springs involved, they're just Rods in precision Tubes, the more Airflow through the Tubes, the higher they rise.
They're useless for balancing the TBs on the Fuel injected Guzzis (the 8V 1200s at least), as they bounce around like crazy at idle.

I don't think you can beat the Mercury Carbtune set-up for sensitivity.

[John Croucher]

A carb tune is measuring the weight of mercury as a standard.  Not the weight of some other liquid in a tube or beer bottle.  Unless you have a  known chemical of equal weight of mercury in tube attached to a scale with the correct index reference points calculated based on the i.d. of the tubing, there is know way to properly set the correct vacuum setting on a carb or set of carbs or f.i. butterflies.  Balancing two or more may be possible, but to get the correct idle vacuum setting is very questionable. 

The density of water compared to mercury is huge. Over 13-1.  Meaning 1 inch on a mercury gage is over 13 inches on a gage with water.    You can be out a couple of inches with a light chemical in tubes and still be within tolerance if compared to mercury gages.

Don't fool your self with these homemade balancing systems. 

[Kiwi_Roy]

We used to use mercury in the instrument shops because but it's pretty much banned as being too dangerous nowadays.
Spilling a mercury manometer in your garage would be considered a major environmental disaster these days.

[John Croucher]

We used to use mercury in the instrument shops because but it's pretty much banned as being too dangerous nowadays.
Spilling a mercury manometer in your garage would be considered a major environmental disaster these days.

It actually evaporates into the air.  Raise the temperature in the area and blow a fan towards the neighbors house should clean up the mess.

[Chuck in Indiana]

We used to use mercury in the instrument shops because but it's pretty much banned as being too dangerous nowadays.
Spilling a mercury manometer in your garage would be considered a major environmental disaster these days.

When I was a kid, a cousin that was in dental school was always bringing me a vial of mercury to play with.
That explains a lot.. 

[LowRyter]

I remember as a primary grade schooler the kid next door had a bottle of mercury -quick silver-  we'd play with it and coat coins with it.  I was a little jealous that I didnt have a bottle.  The thought crossed my mind that I could break a thermometer to get some but I was never that destructive and didn't like there was enough in there to make it worthwhile. 

Were we doing something unhealthy or bad? 

[Kiwi_Roy]

For anyone wanting to try the Corona beer bottles here's a good demo
https://www.youtube.com/watch?v=7D_f05_a74Y
I use a "U" tube manometer filled with engine oil myself but I would give this a try for sure. its compact and self standing.
One thing you might want to do on a Guzzi is finish your hoses off with a short length of rubber otherwise they fall off the nipple when it gets hot.

[John Warner]

A carb tune is measuring the weight of mercury as a standard.  Not the weight of some other liquid in a tube or beer bottle.  Unless you have a  known chemical of equal weight of mercury in tube attached to a scale with the correct index reference points calculated based on the i.d. of the tubing, there is know way to properly set the correct vacuum setting on a carb or set of carbs or f.i. butterflies.  Balancing two or more may be possible, but to get the correct idle vacuum setting is very questionable. 

The density of water compared to mercury is huge. Over 13-1.  Meaning 1 inch on a mercury gage is over 13 inches on a gage with water.    You can be out a couple of inches with a light chemical in tubes and still be within tolerance if compared to mercury gages.

Don't fool your self with these homemade balancing systems.

Idle Vacuum Setting?
You're balancing the Carbs/Throttle Butterflies, not setting idle.
Idle Speed is set with the Slide Stop Screw(s) (on Carbs), with E.F.I. it's controlled by the ECU via an Idle Control Valve.
'Balancing' (or 'Synchronising') is just a comparison of Inlet Vacuums, and the adjustment to get them equal.

[Cdn850T5NT]

Are you not both setting idle mixture on carburetted models (using a combination of highest vacuum achieved and highest engine rpm) - with the Hg columns + ear... and then also adjusting throttle valve take up (play in the cables.... for equality thereof) with the Hg columns?

[Kiwi_Roy]

Are you not both setting idle mixture on carburetted models (using a combination of highest vacuum achieved and highest engine rpm) - with the Hg columns + ear... and then also adjusting throttle valve take up (play in the cables.... for equality thereof) with the Hg columns?

No the manometer has nothing to do with the mixture  AFAIK, it is just used to set the balance.
A manometer or the beer bottles measure the difference in pressure directly
Carbtune sticks or Vacuum gauges measure the difference indirectly
There are many types of manometer, some of them will measure low pressures, fractions of an inch with extreme accuracy.

[Old Jock]

When I was a kid, a cousin that was in dental school was always bringing me a vial of mercury to play with.
That explains a lot.. 

I remember at a school Biology class, the experiment was something to do with germanation I think. There was a glass cylindrical open vessel filled with Mercury and an upturned test tube under partial vacuum. The Mercury rose up the test tube and there was a small gap at the top, in there was some sort of seed or bean

Anyway there was a problem and I can't remember what, but the teacher asked me to literally give here a hand. We were both up to our wrists in Mercury trying to do something, although what is lost in the sands of time, for quite a few minutes.

Given the panic that the stuff generates nowadays I still can't workout how I'm not dead (but perhaps it affected my memory). I know it can have real bad long term affects, so looking forward to that 

As far as U tubes go for balancing I got some unwanted Mercury from my old firm when it went to the receiver and they were junking all sorts.

Years later I managed to find 2 good U tube manometers and then another large single one, both on E-Bay for reasonable money. Now I have a pair, I can use one on each cylinder, or use the large one and connect both cylinders to either side. Before I do use them I check with gauges that the Vacuum is in a range where there is no danger of sucking the stuff through the engine

[Tom H]

No the manometer has nothing to do with the mixture  AFAIK, it is just used to set the balance.
A manometer or the beer bottles measure the difference in pressure directly
Carbtune sticks or Vacuum gauges measure the difference indirectly
There are many types of manometer, some of them will measure low pressures, fractions of an inch with extreme accuracy.

I think I'm confused. On my Loops and EV there is a connection in the manifold to hook a gauge to. Isn't that where both styles are hooked up?

RER: I used to use a gauge similar to that, it was a pain to read on my Loops and you had to try to hold the throttle the same when you checked each side. I now have a pair of vacuum gauges instead.

Tom

[John Croucher]

I remember at a school Biology class, the experiment was something to do with germanation I think. There was a glass cylindrical open vessel filled with Mercury and an upturned test tube under partial vacuum. The Mercury rose up the test tube and there was a small gap at the top, in there was some sort of seed or bean

Anyway there was a problem and I can't remember what, but the teacher asked me to literally give here a hand. We were both up to our wrists in Mercury trying to do something, although what is lost in the sands of time, for quite a few minutes.

Given the panic that the stuff generates nowadays I still can't workout how I'm not dead (but perhaps it affected my memory). I know it can have real bad long term affects, so looking forward to that 

As far as U tubes go for balancing I got some unwanted Mercury from my old firm when it went to the receiver and they were junking all sorts.

Years later I managed to find 2 good U tube manometers and then another large single one, both on E-Bay for reasonable money. Now I have a pair, I can use one on each cylinder, or use the large one and connect both cylinders to either side. Before I do use them I check with gauges that the Vacuum is in a range where there is no danger of sucking the stuff through the engine

Mercury poisoning is extremely rare with less than 500 deaths annually worldwide.  Mostly caused by coal burning and eating fish.

[Old Jock]

I think I'm confused. On my Loops and EV there is a connection in the manifold to hook a gauge to. Isn't that where both styles are hooked up?

RER: I used to use a gauge similar to that, it was a pain to read on my Loops and you had to try to hold the throttle the same when you checked each side. I now have a pair of vacuum gauges instead.

Tom

You're right Tom, I think what Roy was driving at is if you use a manometer or the beer bottle device with both sides atached to the ports you are reading the pressure difference between the 2 ports

If you are using gauges or a Carbtune you are measuring the vacuum generated by each intake manifold and to get the difference you need to subtract the difference of the gauge readings or the height of the sticks.

If I use 2 manometers with one side of each attached to each inlet manifold and the other side to atmosphere I'll be measuring the actual vacuum generated by each manifold. So I'll need to subtract the difference of each reading to arrive at the pressure difference between them, therefore I'm not measuring the pressure difference directly, I'm measuring each inlet manifold pressure directly.

If I just use one manometer and attach each side to the 2 inlet manifolds I measure the pressure difference between each manifold directly

[Old Jock]

Mercury poisoning is extremely rare with less than 500 deaths annually worldwide.  Mostly caused by coal burning and eating fish.

Thanks for that, puts my mind at rest.

[Tom H]

If I understand it right. It appears that both types are measuring the vacuum at the manifold and that it's just two different tools to do the same job.

I think I got it?
Tom