Really simple question.

I know that the prime position is pointing to the rear of the bike, but which way is main and which is reserve. My tap is not marked and I don't really want to run out to find out!

I would be grateful for any advice.

Cheers

Oops!
Bike is a 1990 GSXR400R GK76a

If i remember right. 'Reserve' is toward the front, 'On' is the center position and 'Prime' is toward the back. Both the on and reserve require vacuum to operate.

If the tap body has no on/res/prime letters marking on it ;it may be from another model and it may be that
the instructions just given above are incorrect.

The 76a tap has this identification......some of the other Suzuki taps with 2 outlets have no instruction but can be used to replace a dodgy tap.It does not always correlate to the lever position being the same.

Carry some spare fuel in a container and ride round until you find which position is which.

Better still would be to remove and service the tap/work out the orientation.... those internal tank filters will appreciate it.