1979 Evinrude 4 HP Outboards Service Manual, PN 5424, Page 15Get this manual
TUNE-UP PROCEDURE When an owner brings motor to you for tune-up, or for some minor operating malfunction, the following procedure should be used as guide to determine the cause of the malfunctionWrite down the owner's commentsKeep an accurate card file on your service shop operation Each service operation should be on record as to the: OWNER'S NAME DATE MODEL NOSERIAL NONATURE OF COMPLAINT NATURE OF WORK PERFORMED COST TO THE OWNER WAS WORK PERFORMED UNDER WARRANTY? After writing down the owner's comments, check the motor visually and begin systematic tune-up procedureConsult the Trouble Check Chart to find the causes of any malfunction which may be discovered when tuning up the motor1Remove exhaust cover and cylinder headSlowly rotate flywheel and visually inspect pistons, rings, and cylinders for wear, freeness, and carbon deposits
2Clean carbon from cylinder head and top of pistonsDo not alter piston deflectorSurface and reinstall cylinder head, using new gasket3Inspect spark plugsClean and regap or replace as necessary