How do dyno's work?
 

I've been seeing graphs of dynos and the results printed out. But how does the dyno work? Is the engine slowly revved until it is WOT, or do you go WOT from the beginning and measure the HP as the RPMs increase or as the speedometer increases? I've seen that debate about how a certain graph shows increased horsepower all the way up to 60 mph. I've wondered if the bike can be run to 60 mph in a few seconds or is the speed slowly increased over a longer time?

How do dyno's work?
 

A dyno uses water to create resistance, much the same way a torque converter works. You can check the maximum horsepower levels at any rpm you want. You simply increase the drag until the engine can't maintain that rpm anymore, even wide open, then check the horsepower reading. It's a bit trickier with gas engines, I'm used to checking diesels where you can set any speed you want, and the governor tries to maintain it.