I'm not surprised that the Honda only makes about 51 HP. That's what a 250 2T produces. I don't want to get into it here, but there are several reasons why that extra 200cc's makes a big difference...and it's NOT torque.
That said, a dyno is a tool. You can learn a lot from it. But, it takes out factors because it does not test DYNAMICALLY. It is a static test, much like a flow bench. It does not test dynamically.
If correctly geared (secondary and PRIMARY), and if the rider understands the power curve (which I doubt many do) and rides it accordingly, it will be as fast as 51 hp at 8000 rpms can be. If, someone comes along, builds the same HP, but does it at 10,000 rpm and it is geared accordingly and ridden with the same consideration as above, the one the rev's higher will be faster than the one that only rev's to 8000 rpm. We are talking 4 strokes here. The same principles apply, but 2 strokes have a power cycle twice as many times as does a 4T.
Lap times are important, but...that's why I hate shootouts. Guys jump on a bike, don't adjust the controls and don't spend enough time to get to know the bike. If the bike is very different from what they consider to be the "norm", the bike gets hammered. Ask KTM. They have been trying to sneak up on Asian handling for years.........