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 TestHoses and Pipes
Hose Installation
Install the hoses and pipes, being careful to follow bending
direction. Avoid sharp bending, kinking, flattening or
twisting.
Run the hoses (see Cable, Wire, and Hose Routing section
in the Appendix chapter).
Install the clamp [A] as near as possible to the hose end
...
Spark Plugs
The standard spark plug is shown in
the table. The spark plugs should be
replaced in accordance with the Periodic
Maintenance Chart.
Spark plug removal should be done
only by a competent mechanic following
the instructions in the Service Manual.
Spark Plug
A. Plug Gap ...
Serial number locations
The engine and frame serial numbers are used to register the motorcycle.
They
are the only means of identifying your particular machine from others of the
same
model type. These serial numbers may be needed by your dealer when ordering
parts. In the event of theft, the investigating authoriti ...