Preferred Pre-Mix Ratio??

[impression]

filled up the tank a bit much today and added in a bit too much oil i think. roughly 10or 12 : 1 ratio, after the bike cooled down and after class the thing would want to start and spark for 2 cycles and then wouldn't start again until about 10km later of clutch engaged pedalling.... boy was that a workout up and down hills :S

oh and then the exhaust blew out @ 45km/h (28mph) i rode back up the hill to find the baffle.