i just bought a suzuki 600 katanna and i want to know what the fuel knob position are for up/left/right?

Answer 1

Straight up and down position for the fuelcock
The normal position for the fuelcock is the "ON" position. In this position, no fuel will flow from the fuelcock to the carburetors unless the engine is running or being started

Turning the nob to the right
"Reserve" if the fuel level in the fuel tank becomes too low for the engine to operate with the fuelcock lever in the "ON" position turn the lever to the "RESERVE" position to use the reserve fuel supply. no fuel will flow from the fuelcock to the carburetors unless the engine is running or being started

Turning the nob to the left
"PRI" If the motorcycle has run out of fuel or has been stored for an extended period, there may not be any gasoline in the carburetors. In this instance the fuelcock should be moved to the "PRI" position. This will alow the fuel to flow directly into the carburetors even though the engine is not operating. Upon starting the engine, be sure to return the fuelcock to the "ON" position.

Personaly I ride with the fuelcock set to reserve and have left it there ever since.

Answer 2

Always ride with petcock in the 'on' position. Then if you run out of gas, you will turn it to the 'reserve' position (sucks gas from the very bottom of tank), So you can make it to a gas station to refuel.
If you ride in the 'reserve' position all the time, when you run out, you will be pushing it to the gas station and you also run the risk of sediments or other debris from tank getting into carbs clogging them up.