7. INSPECT CYLINDER HEAD FOR CRACKS Using a dye penetrant, check the combustion chamber, intake and exhaust ports, head surface and the top of the head for cracks. If cracked, replace the head. 8. CLEAN VALVES (a) Using a gasket scraper, chip any carbon from the valve head. (b) Using a wire brush, thoroughly clean the valve. 9. INSPECT VALVE STEMS AND GUIDE BUSHINGS (a) Using a caliper gauge, measure the inside diameter of the valve guide bushing. Guide inside diameter: 6.010 - 6.030 mm (0.2366 - 0.2374 in.) (b) Using a micrometer, measure the diameter of the valve stem. Stem diameter: Intake 5.970 - 5.985 mm (0.2350 - 0.2356 in.) Exhaust 5.955 - 5.970 mm (0.2348 - 0.2354 in.) (c) Subtract the valve stem diameter measurement from the valve guide bushing inside diameter measurement. Standard stem oil clearance: Intake 0.025 - 0.060 mm (0.0010 - 0.0024 in.) Exhaust 0.030 - 0.065 mm (0.0012 - 0.0026 in.) Maximum stem oil clearance: Intake 0.08 mm (0.0031 in.) Exhaust 0.10 mm (0.0039 in.) If the clearance is greater than maximum, replace the valve and guide bushing.