Adjust the engine idle speed periodically on the engine at normal operating temperature.
To adjust the idle speed:

Engine oil and filter change
Throtile cable playValve seat repair
The valve seats (1) for both the intake and exhaust
valves are machined to three different angles. The seat
contact surface is cut at 45°.
Intake valve
Exhaust valve
Caution
the valve seat contact area must be
inspected after e ...
Throttle valve synchronization
Check and adjust the throttle valve synchronization
among four cylinders.
Start the engine and run it in idling condition
for
warming up.
Stop the warmed-up engine.
Lift and support the fuel tank. Refer to “fuel
tank
removal and installation” in section 1g (page ...
Cylinder head related parts inspection
Refer to “cylinder head disassembly and assembly” .
Cylinder head distortion
Decarbonize the combustion chambers.
Check the gasket surface of the cylinder head for
distortion. Use a straightedge and thickness gauge.
Take clearance readings at several places. If
readings exceed the ...