2006 SD Johnson 4 Stroke 9.9-15HP Outboards Service Manual, Page 144Get this manual
POWERHEAD CYLINDER HEAD ASSEMBLY If cracks or other damage are found, replace cylinder head
IMPORTANT: Cylinder head can be resurfaced, using surface plate and #400 grit wet sandpaperMove the cylinder head in figure eight pattern when sanding Inspect and clean water jackets
Check for cylinder head warpage using piece of bar stock or machinist's straightedge and feeler gauge setMeasure distortion across six locationsCylinder head warpage must not exceed 0.002 in(0.05 mm)If measurement exceeds this limit, resurface or replace cylinder head