Multi-Cylinder model uploaded! When setting up bottle chain, use the three-port manifolds for the middle bottles, and the two-port manifolds for the bottles on the ends. You want each bottle to be connected to every bottle next to it in the chain. So, the order for a four-cylinder engine is 2-3-3-2, while a six-cylinder engine would be 2-3-3-3-3-2. Be sure that the connecting hoses reach all the way to the bottom of each bottle, while the hoses that connect to the intakes only just poke through the top. Also, the more bottles you run, the lower the overall fluid level is going to need to be - DO NOT RUN MORE THAN 3/4 OF A SINGLE BOTTLE OF FLUID. If you run excess fluid in the chain, it's possible for one cylinder to suck everything into the one bottle, then up the hose and into your engine, resulting in hydro-lock. The same is true of running only two bottles - never run more than 3/4 the volume of ONE bottle, so that if it all gets sucked into that one bottle, it won't drown your engine and bend/shatter the connecting rods. You have been warned!
Throttle body/carburetor balancing is probably the #1 most-neglected part of motorcycle maintenance, and when people find out how much the tools cost they "Nope!" right out of there. Here's the dirty little industry secret: No expensive tools are required. All you need are a few sealed containers, some flexible hose that won't collapse under vacuum, and a way to put them all together so that each pressure bottle is linked to all the others (pictured).
These little manifolds are sized to fit 1/4" O.D. clear vinyl tubing, and to just fit into the cap of a typical bottle. Bottles of Jack were used for this example, because they are squared off and fit together neatly into an array. Round bottles will work just as well, as long as care is taken to ensure that everything sits nice and flat on the bench. To ensure nothing leaks, gaskets can be made from old inner-tube, silicone sealing tape, cork, or even a schmear of RTV on the under-side of the manifold itself, making sure to get in-between and around the hoses. The holes in the manifold are just small enough to grip the tubing snugly, and should hold a seal without any help, but if you're going the RTV route, might as well just be doubly-sure there are no leaks. If you find that there is a slight leak where the hoses pull through the manifold, this can be solved via a few drops of any type of oil (the more viscous the better), or even a dollop of RTV.
Manifolds pictured were printed using nylon 6,6 weed-whacker line, because that's what I had at-hand that could handle heat and chemical exposure. I believe ABS/ASA could actually be a superior option, as one could use acetone to really seal and fix the tubing into place, as well as help create a form-fitting seal against the mouth of the bottle (wipe on acetone, then immediately screw everything down).
You will need the original bottle caps, as they are what clamps the manifold onto the bottle mouth. Just cut a 20mm diameter hole in the center of the cap (Updated required hole diameter - I rounded down by accident) , and the manifold will slot right in. It needs to be a circular hole, so that the bottle cap can spin independently of the manifold (it's the same way mason jar lids work - the center section stays put sealed against the mouth, while the outer ring spins and clamps down).
Be aware that while any liquid can be used in the bottles, if an organic fluid is used, you will need to open and clean out the bottles after use - mold doesn't make for good sighting fluid. Also for the record, that isn't liquor in the bottles, it's diluted coffee. ;)
BALANCE YOUR INTAKES!