Yamaha Marine Outboards Factory Service / Repair/ Workshop Manual 225G 250B L250B, Page 38Get this manual
INSP ADJ
CONTROL SYSTEM
ADJUSTING THE ENGINE IDLING SPEED
1Measure: Engine idling speed Out of specification AdjustEngine idling speed 730 30 rmin
Measuring steps (1) Start the engine and allow it to warm up for few minutes(2) Install the tachometer onto the spark plug lead of cylinder #1Tachometer YU-08036-A90890-06760