Honda Outboards BF40A/BF50A Service Manual, Page 242Get this manual
12OIL PANPRIMARY GEAR CASESWIVEL CASE 11OIL PANMUFFLER
1, OIL PANMUFFLER
DISASSEMBLYASSEMBLY
Remove the extension case assembly
OIL LEVEL DIPSTICK
OIL PAN GASKET ASSEMBLY: Do not reuseAlways ;=-1 install new gasket
ASSEMBLY: Clean the oil strainer screen with solvent and check the screen for damage, replace if necessary(15) 13.8 2.5 mm O-RING
ASSEMBLY: Do not reuse(14)
EXHAUST PIPE GASKET ASSEMBLY: Do not reuse