2009 Suzuki 400 LTZ Quad Sport Service Manual, Page 180Get this manual
Engine Mechanical:! 1D-38
CAUTION
The valve seat contact area must be inspected after each cut Do not use lapping compound after the final cut is madeThe finished valve seat should have velvety smooth finish but not highly polished or shiny finishThis will provide soft surface for the final seating of the valve which will occur during the first few seconds of engine operationNOTE After servicing the valve seats, be sure to check the valve clearance after the cylinder head has been reinstalledRefer to "Valve Clearance Inspection and Adjustment in Section 0B (Page 0B-5)"
Cylinder bore Inspect the cylinder wall for any scratches, nicks or other damage (Measure the cylinder bore diameter at six places)If any defects are found, replace the cylinder with new oneSpecial tool (A): 0990020508 (Cylinder gauge set) Cylinder bore Standard: 90.000 90.015 mm (3.5433 3.5439 in)