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 TestExploded View
EO: Apply engine oil.
G: Apply grease.
L: Apply a non-permanent locking agent.
Lh: Left-hand Threads
MO: Apply molybdenum disulfide oil solution.
(mixture of the engine oil and molybdenum disulfide grease in a weight ratio
10:1)
R: Replacement Parts
S: Follow the specified t ...
Ignition Switch Replacement
Remove:
Air Cleaner Housing (see Air Cleaner Housing Removal
in the Fuel System (DFI) chapter)
Disconnect the lead connectors [A].
Remove:
Steering Stem Head (see Stem, Stem Bearing Removal
in the Steering chapter)
Using a small chisel or punch [A], turn out the Torx bolts.
...
Engine Installation
Apply molybdenum disulfide grease to the threads of the
adjusting collars [A].
Install the adjusting collars to crankcase backside until
end of the threads.
Install the adjusting collar [A] to the frame until end of the
threads.
Replace the engine mounting nuts with ne ...