Inspect the camshaft sprocket in the following procedures:
If they are worn or damaged, replace the sprocket/ camshaft assembly and cam chain as a set.

Camshaft inspection
Cam chain tension adjuster inspectionGenerator removal and installation
Removal
Drain engine oil. Refer to “engine oil and filter replacement” in
section 0b .
Remove the left side cowling. Refer to “exterior parts removal and
installation” in section 9d .
Disconnect the generator coupler (1).
Remove the generator cover (2).
...
Specifications
Service data
Oil pump
Oil
Tightening torque specifications
Reference: for the tightening torque of fastener not specified in this
section, refer to “tightening torque list” in section 0c . ...
Exhaust control system operation
The excs is operated by the signal supplied from the ecm. The open/close
operation of the excv is performed by
the excva which is controlled by the ecm by changing the current direction of
the actuator motor. The position
sensor (incorporated in the excva) detects the excva movement by measuri ...