1980 Johnson 4HP Service Manual, Page 15Get this manual
TUNE-UP PROCEDURE When owner brings motor to you for tune-up, for some minor operating malfunction, the following procedure should used as guide to determine the cause of the malfunction Write down the owner's comments accurate card file service shop operationEach service operation should record as to the: OWNER'S NAME MOOEL NOSERIAL NONATURE OF COMPLAINT NATURE OF WORK PERFORMEO OWNER COST WAS WORK PERFORMEO UNOER WARRANTY? After writing down the owner's comments, check the motor visually and begin systematic tune-up procedureConsult the TroubIe Check Chart to find the causes of malfunction which discovered when tuning up the motor1Remove exhaust cover and cylinder headSlowly rotate flywheel and visually inspect pistons, rings, and cylinders for wear, freeness, depositsand
2Clean from cylinder head and top of pistons00 not alter piston deflectorSurface and reinstall cylinder head, using new gasket3Inspect spark plugsClean and regap place as necessary4Inspect and test sensor, coils and ignition wiresSee Section for test proceduresCheck for spark each cylinder5Inspect carburetor and choke6Inspect fuel filterReplace filter screen7Check throttle 3adjustmentSee Section