Your other questions:
Premix ratio: It's a personal choice. Fact is your bike will make more power (jetting adjusted) the richer a premix (more oil) you run. At some point it gets to be counterproductive...like when a good oil is running $10 a quart! 40:1 is fine, and will work out with your ratio-rite, too.
50:1 would be fine, too. Again...jetting adjusted.
I've run 32:1 in my bike. Didn't like it. Went back to 40:1, using Amsoil Interceptor. I prefer 32:1 in my Banshees. It works better, imo..and that's all that matters (
my opinion in
my machines, I mean).
Re: '..seems like alot there's oil coming from the exhaust tip...'
I'll translate to suit me........
That isn't related to your premix ratio. Far more likely to be related to your air/fuel ratio.
Re: 'ONE MORE would it help to run mid grade gas over unleaded?'
For one, it's ALL unleaded anymore. I presume you mean, 'mid-grade unleaded..over regular unleaded'.
What 'helps' is to run the grade of fuel the engine requires. Do you know what the spec is for the KDX?
It is (from the KDX spec sheet):
Fuel Required Min 95 Research/90 Avg. Octane
Coinsidering the junk out of any gas station pump is a concoction of crap that doesn't run worth a damn in anything..what NUMBER is on the pump don't mean diddle, either. But...that's what we have to use (unless you use Trick, C12, or some other 'race' fuel). Wanna talk about distillation curves?
Another personal choice thing. I've run every octane available from the local pumps. I prefer 92. I prefer non-oxygenated fuel, too...but I don't have that choice. It's ALL got alcohol in it 'round here.