Valve Guide
Measure the clearance between the valve guide and the valve stem. If the measured value exceeds the limit, replace the valve guide or the valve, or both.
Standard value:
Intake 0.020 - 0.047 mm (0.0008 - 0.0018 inch)
Exhaust 0.030 - 0.057 mm (0.0012 - 0.0022 inch)
Limit:
Intake 0.10 mm (0.004 inch)
Exhaust 0.15 mm (0.006 inch)