Valve Spring Inspection
Precautions: General safety (00)
Valve Spring Free Length and Preload
•Check each valve spring for breakage or weakening.
•Measure valve spring free length and preload.
If measured value is less than limit, replace valve spring.
•Measure valve spring free length and preload.
If measured value is less than limit, replace valve spring.
NOTE:
Weakened valve spring can cause chatter, not to mention possibility of reducing power output due to gas leakage caused by decreased seating pressure.
Valve spring free length “a”
Standard
IN: 44.83 mm (1.765 in.)
EX: 50.56 mm (1.990 in.)
Intake valve spring preload when compressed to 33.9 mm (1.335 in.)
Standard: 126 – 146 N (12.8 – 14.9 kgf, 28.3 – 32.8 lbf)
Limit: 113 N (11.5 kgf, 25.4 lbf)
Exhaust valve spring preload when compressed to 33.9 mm (1.335 in.)
Standard: 186 – 214 N (19.0 – 21.8 kgf, 41.8 – 48.1 lbf)
Limit: 170 N (17.3 kgf, 38.2 lbf)
Spring Squareness
Use a square and surface plate to check each spring for squareness in terms of clearance between the third turn from top of valve spring and the square as shown. If clearance exceeds limit, replace valve spring.
Intake valve spring squareness “a”
Limit: 1.57 mm (0.0618 in.)
Exhaust valve spring squareness “a”
Limit: 2.20 mm (0.0866 in.)
