Remove the carburetor.
Rotate the 1st chamber throttle until the 2nd chamber throttle begins to open.
Without changing the position of the shutters, measure the opening angle of the throttle valve of the 1st chamber, which should be within 47-53°or 5.4-6.4 mm.
In the event of a deviation from the norm, bend the tongue with which the stop of the throttle valve of the 2nd chamber rests on the throttle valve of the 1st chamber.