Hi everyone, I got this old Honda VFR 750 from 1986.
It’s a 4 cylinders bike with Keihin VD carbs of 34, V shaped engine.

I’ve cleaned my carburetors, replaced all the 4 intake mainfolds, replaced my idle jet with a compatible one, replaced mixture screw and overflow screw and all their o-rings, replaced also o-rings around the pipes.
Is always the same story: initially, it starts wonderfully, then the rpms begin to decrease gradually and eventually shutting off completely and making it impossible to restart.

When the bike stalls, there are always at least 2 cylinders emitting a lot of white smoke while the other two do not, but I noticed that they changed last time I mounted the carbs (last time was cylinder #1 and #4, now #3 and 4#).

What could it be in your opinion?

I assured that fuel doesn’t come out from the needle while idling, so I don’t think it could be a overfilling problem (maybe?).
I set the float height at 7mm like service manual reports and replaced the needle valve.
Mixture screw set at 2 and 1/2 turns (always read it on the manual)