i used 4 equal length plastic tubes from Home Depot/Lowe's/ any hardware store.
I connected all 4 tubes at the bottom using t-connectors from an irrigation slow drip system so all 4 shared the same oil.
You should have 4 tubes, with one end open, and one end connected to each other so the only way air can get in is through the 4 open ends. it should look roughly like this:
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i then blocked off the middle two with my thumb, placed one of the remaining tubes in a quart of oil, and the last tube i used to suck oil into the contraption. I then hung the tubes so the oil rested on the side that was joined together with t's. mind you, i used 10 foot long sections of tubing, and hung them of a hook in my garage ceiling. in about a minute or so, the oil will settle down and rest equally in all 4 tubes, like this:
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I then hook the tubes up the the carbs, you can use little 1/8 plastic connectors for a slow drip irrigation system and push them into the carb ports, or i have even seen 5mm welding tips being used as well. as long as the seal is snug and tight, this device works perfectly.
the theory behind this is that the carbs vacuum will fight against each other and raise the oil in the tubes that have greater vacuum in contrast to the other ones. At first i was skeptical, but once i started the bike, this thing actually worked!!!!!
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i could slowly see tube #4 (carb #4, left to right sitting down) rising to the ceiling, while 1 and 2 dropped, so i adjusted the slide on 4 and the other two evened out a bit, the 2 started to rise, etc.... I kept on tweaking until all 4 oil levels where relatively close to one another, establishing a consistent vacuum between the carbs. basically, since 2 is your constant (cannot be adjusted), you want the other 3 to match, i started by closing them all so 2 was the highest, then started with the lowest of the remaining three and brought it up to match. it took a little patience as the sensitivity of this device is actually rather extreme, the littlest of adjustments on the carbs would cause the oil to rise or lower quite a bit. eventually they got pretty close to each other, like this:
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I think this might be easier to look at than say, 4 bouncing needles in a dial gauge, especially if the gauges are not right next to each other. Four 1/8" tubes (what i used), sitting right next to each other might have been an inch and a half wide at the most, REAL easy to see all 4 carbs at once.
I understand you die-hards and the fact that you do not consider this an accurate machine, however, we are not trying to establish a set vacuum reading for the carbs when synching, just trying to get consistent vacuum between the carbs in relation to one another, and this machine did the trick. I understand that this does not, or will it ever, establish a base point in carb 2 as being within spec, and this device assumes that your carb 2 is withing spec.
I think all in all, i might have spent $10 in total parts for this device.
Google (or whatever search engine you prefer) "Homemade Manometer" (although this definition is incorrect, this is not a manometer), and you should see several threads with pictures of various contraptions.
