Today I installed the carburetors and put everything together. The motorcycle starts much easier and revs up easier. I set the TPS sensor and checked the synchronization. It turned out that the problem still exists. I swapped vaku and they showed different readings. The two from the right matched, the next two indicated different readings. It turns out that the first two are fine and I set all the throttles according to them. But I'm not sure and I'll go to a mechanic to set up the synchro. I would not buy cheap Chinese vacuum gauges a second time. Thanks Unfazed for your patience and valuable informations
https://youtu.be/mK-5cj-gzJc
