1971 Johnson 125HP outboards Service Manual, Page 14Get this manual
2- SPECIAL NOTE Piston ring condition should be determined before continuing tune-upGum and varnish deposits on rings or pistons may be removed with an application of OMC Accessory Engine CleanerIf pistons and rings are considered to be in satisfactory condi- tion for continued service, remove carbon, surface and reinstall covers, using new gasketsCrankshaft end play must not exceed specificationsSee Section 2Clean carbon from cylinder heads and top of pistons with careDo not alter deflectorsReplace upper bearing crankshaft sealSurface and reinstall cylinder heads, using new gasketsTighten cylinder head screws to specified torqueInspect spark plugsClean or replace as necessaryInspect and test sensor, coil, and ignition wiresSee Section for test proceduresCheck for spark on each cylinderInspect carburetors and automatic chokeInspect fuel pump and linesReplace filter element and gasketSynchronize carburetor linkageSee Section 4Inspect electric shift operationSee Section for test proceduresCheck propeller for conditionSee Section 6