Just got a KDX, help needed

I bought an 88' KDX about a month ago. A friend of mine has a KX80, rode it and loved the instant power (i'm a 4 stroke guy). I decided to get a KDX after reading on here on how great they are for the woods, and also not being able to find an XR 250 at a good price. Well, how glad I am I bought this bike and not something else! It's pretty much just an old beater and looks pretty bad, but it seems lightyears ahead of my old 78' XL250. Finally was able to take it out today on the trails after seeing one of my old buddies. He has a 95' CR125 that is basically "new" since he's replaced about everything on it. We are both pretty much intermediate level trail riders, and that KDX had no problem keeping up with him, and actually I was going a lot faster than him through most parts of the trails. Not to mention that this bike is pretty much stock except the baffle was taken out of the pipe, and it has no headlight, only a number plate.

Anyhow, I'm new to 2 strokes and especially Kawi's. I have a few questions. First, where is the idle adjustment screw? This bike will not idle. Also, what ratio premix should I run? The guy I bought it from said he runs 50:1 in it. My CR buddy runs 36:1 in his. Big difference there. I ran 50:1 in it and it runs fine except for the idle problem. I have no idea what jetting it's got in it, but it runs fine and I don't know much about 2 smokes so I figured I would just leave it.

Anyhow, sorry if these are old questions, but it didn't come w/ a manual and I'm new to the 2 stroke bikes. Thanks

The NGK plug and twin air filter are both brand new, this is the 1st time I've ridden the bike for longer than 10 min. since putting them in about a week ago. Compression I don't know about, I'm sure a new top end wouldn't hurt it, but it starts great and has plenty of power for me, so I'm satisfied with it like it is. Thanks for the help guys, and I'll try to get a manual sometime soon.