Honda BF20A-BF25A, BF25D-BF30D Outboard Motors Shop Manual., Page 19Get this manual
CYLINDER COMPRESSION 1) Put the remote control lever or gearshift lever in the neutral position2) Disengage the emergency stop switch clip from the emergency stop switch3) Put the choke knob or choketfast idle lever in the normal run position4) Remove the engine cover and all the spark plug capsRemove the all spark plugs5)Carefully disconnect the throttle rod from the throttle cam (P3-10)6)Install compression gauge in one of the spark plug holes7) Manually hold the throttle cam in the wide open throttle position8) Using the ignition key, starter button, or recoil starter, operate the starter until the highest compression reading is obtained-