Honda BF9.9A-BF15A Outboard Motors Shop Manual., Page 46Get this manual

HONDA BFSSA-BF15A
THERMOSTAT
Suspend the thermostat in heated water and check for the valve liftMeasure the water temperature when the thermostat starts opening

f 11THERMOMETER

Don't let the thermometer or the thermostat touch the container; this may cause false reading
[2] THE RMOSTAT

• ATV
• Jet Ski
• Outboard Motors
• Personal Watercraft
• Snowmobiles
• Stern Drives