i have a kx 125 2 stroke.the exhaust smoke is black and stians the mud gaurd. is the mix wrong or is it something else?

Hi brendon,
As long as its full power and running well i would say it was to rich,petrol & oil. If u dont race full bore on a 2 stroke crosser the oil does build up and as i found out oils up the plug the only cure i found was to go from 40- 1, 50-1 that cured that oiled plug problem then the black plug problem was cured by lowering the needle in the carb. Most xers run rich fuel & oil to maximize lubrication.Just experiment with different oils also. Hope this helps.
Zrick.

kawas i run my 250 at 50-1 and i still get that unburned %$£! flyin out but the 50-1 mix kept it minimal so thats probly the best way to go i think