Yamaha 115-225 HP Outboards Service Manual, Page 66Get this manual
-4) While keeping the stopper in contact with the full-retard adjusting screw, measure the fully-retarded ignition timing with the timing lightIf the timing is out of specification, adjust it by turning the screw PERIODIC SERVICE
When measuring the ignition timing on the fullretard side, keep the specified idle-speed (Refer to page 2-1)
Fully-retarded side ignition timing: 115-130: degrees ATDC 225: degrees ATDC 150200: degrees ATDC
5) While keeping the magneto control lever in contact with the full-advance adjusting screw, measure the ignition timing with the timing lightIf the timing is out of specification, adjust it by turning the screw