7. CYLINDER HEAD/VALVES ATV 150/125 Measure each valve guide I.D. Subtract each valve stem O.D. from the corresponding guide I.D. to obtain the stem- to-guide clearance. Service limits: IN : 0.06 mm (0.0024 in) EX: 0.08 mm (0.0032 in) If the stem-to-guide clearance exceeds the service limits, replace the cylinder head as necessary. VALVE SPRING FREE LENGTH Measure the free length of the inner and outer valve springs. Inner : 38.2 mm (1.528 in) Outer: 44.3 mm (1.772 in) Measure compressed force (valve spring) and installed length. Replace if out of specification. Service limits: IN : 7.78.9 kg (at 33.7mm) EX : 19.522.5 kg (at 38.4mm) Measure the spring tilt. Replace if out of specification. Service limits: IN : 1.7 mm (0.068 IN) EX : 1.95 mm (0.078) 7-9