What is the correct oil to fuel ratio for a 1984 Kawasaki KDX 200?

I have a 1986 rm 250 and I mix it 35 to 1 I just got the bike rebuilt then once its broken in I was told go 50 to 1

I would stick to around 50:1 almost always, you can lean the oil out alittle and go 40:1, but the leaner you go the more chance you take on friction building up and then the motor will sieze. Almost everything I own that is two cycle (minus my old chainsaw) is 50:1 and the chainsaw that's 40:1, I run it at 50:1 and it runs fine and alot of power. I would check the spark plug after 3-4 hour of riding and see if it still is pretty clean and then go 40:1 if the spark plug is getting gunked up.