ENGINE MECHANICAL — Cylinder Head EM-45 (f) Gradually heat the cylinder head to approx. 90°C (194°F). (g) Using SST and hammer, drive in a new valve guide bushing until the snap ring makes contact with the cylinder head. SST 09201-70010 (h) Using a sharp 6 mm (0.24 in.) reamer, ream the valve guide bushing to obtain standard specified clearance (See page EM-43) between the valve guide bushing and new valve. 11. INSPECT AND GRIND VALVES (a) Grind the valve only enough to remove pits and carbon. (b) Check that the valve is ground to the correct valve face angle. Valve face angle: 44.5° (c) Check the valve head margin thickness. Standard margin thickness: 1.3 mm (0.051 in.) Minimum margin thickness: 0.5 mm (0.020 in.) If the valve head margin thickness is less than minimum, replace the valve. (d) Check the valve overall length. Standard overall length: 98.15 mm (3.8642 in.) Minimum overall length: 97.75 mm (3.8484 in.) If the valve overall length is less than minimum, replace the valve.