1972 Johnson 4HP Outboard Motor Service Manual, Page 11Get this manual
TUNE-UP PROCEDURE When an owner brings motor to for tune-up, or for some minor operating malfunction, the following procedure should used as guide to determine the cause of the malfunctionWrite down the owner' commentsan accurate card file your service shop operationEach service operation should record as to the: OWNER'S DATE MODEL NOSERIAL NONATURE OF COMPLAINT NATURE OF WORK PERFORMED COST OWNER WAS WORK PERFORMED UNDER WARRANTY? After writing down the owner' comments, check the motor visually and begin systematic tune-up procedureConsult the Trouble Check Chart to find the causes of any malfunction which discovered when tuning the motor1Remove exhaust cover andcylinder headSlowly rotate flywheel and visually inspect pistons, rings, and cylinders for wear, freeness, and carbon deposits 234567891011
If pistons, cylinders, and rings are considered to in satisfactory condition for continued service, reinstall cover, using new gasket