Honda BF75 BF100 Outboards Service Manual, Page 25Get this manual
HONDA BF75BFIOO
3SPARK PLUG CLEANINGADJUSTMENT
(11 Remove carbon and other deposits from the spark plugs with stiff wire brush (21 Measure the spark plug gap with feeler gaugeTo adjustbend the negative (grounded) electrode 0.6-0.7 mm (0.024-0.028 in)
I STANDARD PLUG GAP: .6-0.7 mm 10.024-0.028 in} I
STANDARD SPARK PLUG: DR-5HS (NGK) ALTERNATE: DR-4HS (NGK) NOTE: If the DR-SHS plugs tend to get heavily carbo ned or wet fouledtry the DR-4HS type
4IGNITION TIMING ADJUSTMENT
CONTACT BRAKER TYPE
(1) Connect .timing tester or ohmmeter as shown (2) Rotate the flywheel to align the "F" mark on the flywheel to the index mark on the starter case At this time the contact breaker points should just start to open (15B.T.D.C .1 (3) To adjust the timingloosen the breaker plate locking screw and move the contact breaker plate to achieve correct timingRetighten the locking screw(4) Rotate the flywheel one full turnand check ignition timing for the other cylinderReadjust the contact breaker pointsif necessary60 the ignition timing will be as correct as possible for both cylinders