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 TestSwingarm Installation
Visually inspect the chain guide [A].
Replace the chain guide if it shows any signs of abnormal
wear or damage.
Apply a non-permanent locking agent to the threads of
the chain guide bolt [B].
Apply plenty of grease to the lip of the oil seals [A].
Be sure to install the oil seals ...
Crankshaft Removal
Split the crankcase (see Crankcase Splitting).
Remove:
Connecting Rod Big End Nuts [A]
Connecting Rod Big End Caps [B]
NOTE
Mark and record the locations of the connecting rods
and their big end caps so that they can be reassembled
in their original positions.
Remove the crank ...
KIBS Motor Relay Inspection (Service Code b 35)
Check the KIBS motor relay fuse (25 A) [A] (see Fuse
Inspection in the Electrical System chapter)
If the fuse is good, check the wiring continuity as follows.
Disconnect:
Battery Positive Cable (see Battery Removal in the Electrical
System chapter)
KIBS Hydraulic Unit Lead Connector (see ...