I finally managed to "open" my motorbike and test the device.
I could only connect 2 out of 3 throttle bodies, because the 3rd is in a bad position.
The main problem is that the values read are unstable, they change continuosly.
I thought that reading a value in a random moment, could measure anywhere during the four-stroke cycle.
In order to try to solve this, I read 250 vacuum values per sensor (which takes around 300ms each) and take the lowest vacuum value in order to catch the intake cycle.
It's better this way, but still to jumpy to make a precise measure.
At the moment I don't have any better idea in order to stabilize the readings.