Ok, this really confused me yesterday so I'm wondering if this has happened to anyone else. Background: 2013 250sx, jetting is great and runs mint. Almost 17 hours on the bike and never any problems at all (all mx riding). Issue: Yesterday, I go out on track with buddies wife and tow her around to show her lines and whatnot. This is literally the only time I've gone out and putted around without really going wide open at all. I just went around for 3 laps and pulled off. At this point my motor was smoking and I noticed coolant sprayed all over the front. It seemed like it spewed coolant from the overflow line (where it connects to the frame in front). I let it cool down and replaced the bit of coolant that leaked out and then rode a few sessions how I normally do, riding it hard. It was fine and never lost anymore coolant. WTF!?