The cams should have IN and EX clearly cast on them. Looking from the right side of the bike you would fit the exhaust cam with the 'E' facing the front, inline with the gasket surface, this will leave the '2' at the top, you would count 20 pins from this and fit the inlet cam with the '3' at the top, arrow points at the 20th pin. This is done with the arrow mark on the pickup trigger facing the 't' on the case and everything intention with the motor turned the way it runs. hope this makes sense.