The prime is used after you run out, or some other interruption in the fuel line (changing the filter etc)
prime allows the free flow of fuel to the carbs under gravity, the fuel is sucked into the carbs when the tap is ON or RESERVE, so you would have the tap to ON when removing the tank from the bike, you still get a small dribble of fuel left in the tubing, if the tap was on PRIME,,,,,,, it would piss out
Foamy has a point you kno, every day has a different name (I learned this at school long time ago), could Friday be Fann,,,,,,,,,,,,,
one of the moderators has taken my post down !