What I'm thinking, though, is that when I'm watching these guys take to the track on their four-strokes, they don't hold it at the limiter necessarily, but as soon as the back tire hops or when they're getting on the power to start a landing, it revs to the moon and hits the limiter. For example in the video in the OP of this thread, his RPM doesn't seem all that high when the wheel is touching the ground, but the instant it goes into the air it's spinning at full blow. If it were my bike and I wanted to avoid rebuilding it every week, I'd want a really good insurance policy against revving to the moon. With a two-stroke it's not so bad because they don't seem to break (example, I once accidentally shifted from fourth to first on the 120 and it's still going on those parts) but with a four-stroke I'd definitely want a safety net to save my assets.