Okay.... New here and will be blasting you guys with questions that are common sense bs to y'all, but I'm two stroke stupid. Just to start it off, I road raced with CCS for 7 or 8 years and I have a 2013 R1 that my neighbors HATE. So I'm not completely bike stupid, I've just never had any exposure to two strokes. It'll make for some good learning experiences with my sons and I. So... I got my son his first bike. It's a 99 YZ250 that runs really well. Doesn't sound 100% stable and a stand alone idle, but it hasn't died. I did find the manual posted on here, which will be a big help when I sit down to sift through the several hundred pages. Until then, I have a few basic getting started questions. 1. Mixing the fuel. My son's not going to be riding it hard for a while. I assume 40:1 is good enough? 1.1. I rejetted my very first bike; a CBR F3 many many many years ago. I only did it because the guy at the bike shop told me it needed it and I can't recall why. What indication is there that the jetting needs tweaked? 2. What kind of oil do you mix with the gas? Same stuff that I put in the weed eater or something special? 3. I've read that 14 psi is a good tire pressure for pavement and fields. This correct? A friend owns a huge wear house and I don't know anyone in Michigan with much land to play on. He has a huge field in the back and acres of open parking lots on the weekend and a mile long road in the middle of nowhere to play and practice on. The nobbies won't offer much traction; but what's best for going from grass to pavement? 4. I've read about top end rebuilds at 30 or so hours. Is this true and what indications are there that it's ready for that? 5. Gear oil. What do you use? 6. The chain seems to be far looser than I'd ever have on the track or street. What's your method of measuring chain tension? 7. With these questions, I'm sure you can understand the grasp (or lack there of) that I hold on two strokes and dirt bikes in general. Anything else I should know or look into?