2006-2010 Suzuki DF150 / DF175 4-Stroke Outboards Service Manual, Page 252Get this manual
POWER UNIT
Manifold seating faces distortion Using straightedge and thickness gauge, check cylinder head to manifold seating facesManifold seating faces distortion Service limit: 0.10 mm (0.004 in) If measurement exceeds service limit, resurface or replace cylinder head