Erik, aka Laegereliminator on here is a great resource on this topic. He built his protrax from scratch. I'm planning on doing one specifically for mx as well. I jump the shit out of my current bike with a +4 on dirt and it flies like a dream. Gyro in the air is all about suspension setup and brake and throttle control. Cornering is where it fails. There are a few other guys pretty serious about 250r geo frames on here. Depending how busy they are, power in numbers might get a run going.