2007-2009 Yamaha F15/F20 Outboard Service Manual, Page 134Get this manual
Cylinder head Cam lobe a: Intake: 28.54628.646 mm (1.12391.1278 in) Exhaust: 28.58228.682 mm (1.12531.1292 in) Cam lobe b: Intake and exhaust: 23.9524.05 mm (0.94290.9468 in) 2Measure the camshaft runoutReplace if above specificationCamshaft journal diameter c: 21.96721.980 mm (0.86480.8654 in) Camshaft journal diameter d: 33.93533.955 mm (1.33601.3368 in) Cylinder head journal inside diameter e: 22.00022.021 mm (0.86610.8670 in) Cylinder head journal inside diameter f: 34.00034.025 mm (1.33861.3396 in) 4Check the automatic decompression actuatorReplace the camshaft if damaged or worn 1 3