how can i reverse the gears on my mercury 500 thunderbolt??

hi
your engine will rev out in reverse because the prop is only designed to work marginaly that way, so there is less resistance on it, the gearbox gear ratio is the same in forward as reverse so altering the selection will not work.
your engine/power head is only producing enough power to push your boat/ engine forward up to 50% as the prop has full resistance this way(witch is harder work for the engine) i would guess you have a fuel or ignition timing problem the "blue band" or thunderbolt engine has small filters behind the blue covers on the carbs are they blocked? are the fuel pump diaphragms working(they only need to have a pin prick smaller than the eye can see to be useless).

Greasy
September 2010