6. 4-STROKE: CYLINDER HEAD/VALVES VITALITY 50 VALVE SPRING INSPECTION Measure the free length of the inner and outer valve springs. Service Limit: Inner: 28.4mm replace if below Outer: 31.5mm replace if below Measure compressed force (valve spring) and installed length. Replace if out of specification. Service limits: IN : 56kg(at 20.45mm) EX : 9.511.5kg(at 23.5mm) Check the intake manifold and O-rings for wear or damage. O-ring 6-12