1974 Johnson 135 HP Outboard Motors Service manual, Page 59Get this manual
CLEANINGINSPECTIONAN REPAIR
CYLINDER BLOCK AND CRANKCASE
Check cylinder walls for excessive wear, and check cylinder ports for carbon accumulationCylinder walls wear in various degrees depending on lubrication and conditions under which the motor is operatedMajor portion of wear is in the port area and the area covered by ring travelCheck cylinder for ize and wall straightness by using an inside micrometer or dial bore indicatorRefer to Section for specified dimensionsIf wear is greater than .003", replace cylinder block, or rebore block for oversize pistonsPistons and ring sets are availableSee Section 2, Specifications