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Carbtune query? 10 Jun 2020 15:15 #827794

  • 650ed
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Warren3200gt wrote: There is nothing wrong with vacuum gauges as long as you are certain that all the gauges read exactly the same for a given vacuum ....


This is very easy to check. You switch which carbs the hoses are connected to and the readings should be the same. If, for example, the reading for one carb changes when you switch the hoses one or more gauges has a problem. Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)

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Carbtune query? 10 Jun 2020 15:29 #827797

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Yes ed, im guessing you didnt read the whole thread. That what i did with a morgan carb tune and was getting a 25% variance between the lowest and higest reading.

Z1000J2 somewhat modified!

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Carbtune query? 10 Jun 2020 17:19 #827817

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To verify your vaccum clocks:



I did before i use my vaccum clocks:

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Carbtune query? 11 Jun 2020 06:24 #827853

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That's a pretty nice looking set of vacuum gages Scirocco. Must be expensive I'll bet. Can they be individually zeroed out or calibrated?
Rick H.

1977 Kawasaki KZ-1000A1

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Carbtune query? 11 Jun 2020 07:38 #827868

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Rick H. wrote: That's a pretty nice looking set of vacuum gages Scirocco. Must be expensive I'll bet. Can they be individually zeroed out or calibrated?


234 Euros = $266.

1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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Carbtune query? 11 Jun 2020 07:44 #827869

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I found these work very well and while not inexpensive are at least somewhat reasonable:





Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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Carbtune query? 11 Jun 2020 07:48 #827870

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I previously had a set of these and found them to be totally inaccurate junk. I would NEVER recommend them even to an enemy:



Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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Carbtune query? 11 Jun 2020 09:40 #827883

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Here's an idea I had, but never built it. They look different but are functionally the same. It's easier to connect through a rubber stopper at the top rather than connecting the bottoms of glass bottles. The problem with complex structures like this is it's hard to chase down all the small leaks.

American Science and Surplus has a great selection of rubber stoppers and tubing connections, and other science glassware.
Sometimes the brick & mortar stores seem to have more than what the online store has. I know I've seen the 2 and 3 hole stoppers there. Maybe they're gone now.

www.sciplus.com/s/?p=1&q=stopper





The siphon tubes will self-prime when unequal vacuum is applied.


These are my notes form 7 years ago. I think I may have posted this somewhere before.

"In my opinion, the cheapest of the home-made ones are not of a very good design.
There are a few things that all of them should have, but some of them miss.

First and foremost, is the restrictor, which should be as close to the connection to the motor as possible. Without it, you actually alter the vacuum inside the manifold. So after you remove the manometer, the vacuum in the manifolds will be different from when you did the sync. Without restrictors, if the manometer tubing etc. is not perfectly identical, then the manifold vacuum will no longer be the same for all cylinders once the manometer is removed. The restrictors help isolate the manometer's volume of air from affecting the manifold vacuum.

The problem with cheap plastic restrictors, is that they flex. This means when there is a vacuum pulse, they restrict the air more than when there is no pulse. They then act like a valve. Since they all flex slightly differently, they will each affect the vacuum reading differently. The restrictors must be non-flexible, and cleanly drilled with no burs. The restrictors don't have to be identical, they just have to not flex and be very small. The size of the restrictors determine how much the manometer will pulsate, but do not affect the average measured vacuum.

Obviously, because water is only 1/13th as heavy as mercury, we can't use a gauge manometer. It would have to be 20 feet tall. So it will have to be a sealed system. This will show relative differences in vacuum. To have a decent sync on the carbs, you want them all to be within about 10 mm of mercury. This equates to 130 mm of water, or about 5 inches of water. But to make it even better, lets say they should be within 5 mm of mercury, and thus 2.5 inches of water.

To prevent the water from being sucked up into the engine, the manometer must use rather large/tall tubes, or better yet, bottles. By limiting the amount/height of water in the bottles, it will prevent the water from being sucked in as liquid. A tiny bit of vapor or spray won't hurt. So the bottles will start with 2.5 inches of water above their lower connection tubes, this means the bottles need to be at least 10 inches tall. Taller is better.

Unfortunately, soda bottles won't work. They are essentially water-bags when a vacuum is applied. You must use ridgid plastic bottles or glass or metal containers with windows. That's the part that makes the project difficult... acquiring the bottles ."

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Carbtune query? 11 Jun 2020 10:13 #827885

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I also had another idea for a sync. This came up because my buddy is mostly a 2-stroke guy and they apparently don't use vacuum for synching. It's rougher and simpler, just throttle-slide opening measurements.

My idea was you could measure the time between cylinder firings to decide which cylinder was providing more power. When a more powerful cylinder fires, the time to the next cylinder firing will be shorter. And conversely when a weaker cylinder fires, the time to the next cylinder firing will be longer. You then open the throttle a bit on the weaker cylinder or close the one on the stronger cylinder. When the time between firings is equal, the idle will be smooth.

There are some issues, though. Most importantly, the ignition timing has to be very accurate (at idle). On four-strokes, like the Kz, you would also need a vacuum pulse on the #1 cylinder to make sure the timing device is measuring the time on the correct cylinder, and not the waste-spark cylinder. This is not a problem on two-strokes since they fire every revolution.

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Carbtune query? 11 Jun 2020 10:36 #827889

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Hows lockdown going for you loudhvx ? :laugh:

Z1000J2 somewhat modified!

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Carbtune query? 11 Jun 2020 10:43 #827892

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:laugh: Well, I've been working, but yes, extra time leads to a bunch of extra project ideas that I will prob never get to. Those ideas were from years ago though.

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Carbtune query? 11 Jun 2020 13:35 #827922

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Rick H. wrote : Can they be individually zeroed out or calibrated?


Yes, the new made Boehm vacuum gauges are adjustable for calibration if needed.

www.boehm-synchrontester.de/technische%20daten.html



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