2000-2005 Yamaha F40B Outboard Service Manual, Page 104Get this manual
1 POWER UNIT Oil pressure at idling (at 55C (131F 150kPa (1.5kgfcm21psi) (5) Remove the oil pressure gauge(6) Install the oil pressure switch
ADJUSTING THE VALVE CLEARANCE
NOTE: _ Valve clearance adjustment should be carried out when the engine is "cold"Do not adjust the clearance as "removed cylinder head"
1Measure: Intake valve clearance