2005 Yamaha F90TR 90HP Outboards Factory Service Manual, Page 76Get this manual
Power unit
Checking the valve clearance
CAUTION:
Do not turn the flywheel magnet counterclockwise, otherwise the valve system may be damaged Do not remove the ignition timing pointer Do not turn the flywheel magnet or the driven sprockets when the timing belt is not installedOtherwise the piston and valves will interfere with each other and be damagedNOTE: For removal and installation procedures of the timing belt, driven sprockets, and camshafts, see the applicable procedures in this manual1Remove the flywheel magnet cover 1, filter 2, and spark plug wire cover 3, disconnect the spark plug wires 4, fuel hoses 5, and blowby hose 6, and then remove all spark plugsS6D85140