Honda BF50 (5HP), BF5A Outboard Motors Shop Manual 2014, Page 34Get this manual
BF50BF5A bINSPECTION THERMOSTAT
1) Inspect the thermostat visually for damage2) Suspend the thermostat in heated water to check its operationDo not let the thermostat or thermometer touch the pan or false readings will resultStart to open Valve lift 54C (122-129F) 3-4 mm (0.12-0.16 in) when heated to more than 54C (129F) for five minutesTHERMOMETER
THERMOSTAT
3) Replace the thermostat if the valve stays open at room tem perature, or if it responds at temperatures other than those specified
VALVE LIFT
FUEL PUMP
Check the friction surface on the push rod for wear using feeler gauge, and replace the push rod with new one if it is worn more than .05 mm (0.002 in)