Refer to “oil pan / oil pressure regulator / oil strainer removal and installation” .
Oil pressure regulator
Inspect the operation of the oil pressure regulator by pushing the piston with a proper bar.
If the piston does not operate smoothly, replace the oil pressure regulator with a new one.

Oil strainer
Clean the oil strainer if necessary.
Inspect the oil strainer body for damage. If necessary, replace it with a new one.

Oil pan / oil pressure regulator / oil strainer
removal and installation
Oil cooler / oil cooler hose inspection and
cleaningEngine components removable with the
engine in place
Engine components which can be removed while the engine is installed on the
frame are as follows. For the installing
and removing procedures, refer to respective paragraphs describing each
component.
Center of engine
Item
Removal
Inspection
Installation
...
Oil cooler / oil cooler hose removal and
installation
Refer to “electrical components location” in section 0a .
Removal
Turn the ignition switch off.
Remove the left side cowling. Refer to “exterior parts removal and
installation” in section 9d .
Drain engine oil. Refer to “engine oil and filter replacement” in
section 0b .
...
Piston ring removal and installation
Removal
Remove the piston. Refer to “engine bottom side disassembly” .
Carefully spread the ring opening with your thumbs
and then push up the opposite side of the 1st ring to
remove it.
Note
do not expand the piston ring excessively
since it is apt to be broken down. ...