Review on ALPHA MOTO Universal Motorcycle Vacuum Carburetor Synchronizer Synchronization Balancer Carb Sync Balancing Gauge | Compatible With Honda Yamaha Kawasaki Suzuki GS KZ XS CB 550 650 750 850 900 BMW by Steve Jones

If you tried to use this ready-to-go carb balancing bike, you'd have the worst wheel in the store. Each needle pointed in a different direction with a broad border. To bring them closer I had to daisy chain them all with a common vacuum source and then adjust each one individually. A few of them were very tight. I was able to get to the point where they all crossed at about 10 inches and were close enough that between 5 and 15 didn't matter. They're not all linear to each other, so if one says 20, the other would be 25. Pick a value that's close to your goal, and balance all four around that goal to get closer. Unless you have a truly calibrated gauge actual numbers are a guess, but actual numbers are not necessary for basic motorcycle carburetor timing. The only reason to use 4 sensors is for convenience when they are calibrated against each other. The best way is to use a sensor and draw 4 lines in a sensor. The kit comes with everything else you need, but you'll need tees to do a one-sensor approach. A cheap source of tea BTW is to use Rainbird or regular drip irrigation parts.