2004 SR Johnson 2-stroke 40, 50HP Service Manual, Page 194Get this manual
POWERHEAD INSPECTION must be more than 0.004 in(0.10 mm) smaller than the major diameter
Ring End Gap Specification
Standard or Oversize rings
0.010 to 0.022 in(0.25 to 0.56 mm)
IMPORTANT: Ring end gap increases approximately 0.003 in(0.076 mm) for each 0.001 in(0.025 mm) increase in cylinder bore diameterDO NOT exceed cylinder oversize dimensionUse machinist's straightedge to check for proper ring clearancePosition piston rings on pistonPush rings into groove and hold straightedge against the side of the pistonRings must be even or just below the surface of piston Rings must move freely in piston ring groove If straightedge does not touch piston, remove the ring and clean ring grooveDowelpin