Harley Davidson Sportster models 2011. Service manual — page 20

2. Soak cylinder head in an aluminum-compatible cleaner/solvent to loosen carbon deposits.

3. Wash all parts in non-flammable solvent, followed by a thorough washing with hot, soapy water. Blow out oil passages in head. Be sure they are free of sludge and carbon particles. Remove loosened carbon from valve head and valve stem using a wire wheel. Never use a file or other hardened tool which could scratch or nick valve. Polish valve stem with very fine emery cloth or steel wool.

4. See Figure 3-52. Check head gasket surface on head for flatness. Machine or replace any head which exceeds SERVICE WEAR LIMIT of 0.006 in (0.152 mm).