You can run what you are comfortable with, but anything from 40 to 60:1 is the norm. KTM's are notorious for requiring the owner to rejet to get the bike to run clean. Jump onto KTMtalk.com, they will help you get it jetted properly. Personally I run my 2000 300 EXC at 45:1. Just jet it to your oil and ratio mix ratio, and get ready to have muscle cramps in your face from smiling so much...
Congratulations on the new bike, you won't be disappointed... By the way, I am jealous...
