2003 ST 4 Stroke 9.9/15HP Johnson outboards Service Manual, Page 9Get this manual
GENERAL INFORMATION ENGINE BREAK-IN
ENGINE BREAK-IN
The first 10 hours are critically important to ensure correct running of either brand new motor or motor that has been reconditioned or rebuiltHow the motor is operated during this time will have direct bearing on its life span and longterm durabilityBreak-in period: 10 hours
WARM-UP RECOMMENDATION
Allow sufficient idling time (more than minutes) for the engine to warm up after cold engine starting
THROTTLE RECOMMENDATION
NOTE: Avoid maintaining constant engine speed for an extended period at any time during the engine break-in by varying the throttle position occasionally