This would depend on what type of oil you will be using for your premix. The oil base stock is either petroleum, semi-synthetic or synthetic oil and is mixed with gas at a ratio ranging from 16:1 (petroleum) to as high as 100:1 (synthetic). I personally ride a 2001 Kawasaki KDX200 that I run Yamalube 2R at 36:1 with no problems. Although synthetics say you can mix them at 100:1 I would not, that seems way too lean to me.
There is no fuel/oil ratio, the 03 KTM 450 EXC is a four stroke. See link below.
32:1 ratio
I personally use 32:1 of amsoil and regular unleaded gas for my ktm 125 sx 2003.
60:1
gas oil ratio for 1994 ktm 50 junior
My manuel recommends 40 to 1on my 2001 ktm sx I've never had any problems with it..
50/1
.7 L
50ml of oil to every litre of petrol
40:1
In the picture on the internet does Serj Tankian realy do drugs?
32 to 1 or 50 to 1