When the engine is running, the air intake valve is lifting up.
If the valve does not operate properly, check the air intake solenoid valve hoses for leak.
If there are no leaks, check the air intake solenoid valve.

Air Intake Solenoid Valve Unit TestTiming Rotor Installation
Install the timing rotor [A] on the crankshaft [B] with their
teeth [C] aligned.
Holding the timing rotor with the flywheel & pulley holder
and tighten the bolt.
Torque - Timing Rotor Bolt: 39 N·m (4.0 kgf·m, 29 ft·lb)
Special Tool - Flywheel & Pulley Holder: 57001-1605
I ...
Special Tools
Fork Oil Level Gauge:
57001-1290
Vacuum Gauge:
57001-1369
Hand Tester:
57001-1394
Throttle Sensor Setting Adapter #1:
57001-1400
Peak Voltage Adapter:
57001-1415
Needle Adapter Set:
57001-1457
Throttle Sensor Setting Adapter:
57001-1538
Measuring Adapter:
57001-1700
...
Upper Fairing Assembly Removal
Remove:
Lower Fairings (see Lower Fairing Removal)
Center Inner Fairing (see Center Inner Fairing Removal)
Upper Inner Fairings (see Upper Inner Fairing Removal)
Windshield (see Windshield Removal)
Disconnect the front turn signal light lead connector [A]
(both sides).
Remove the bo ...