In the then weekly magazine 'Motor' 60 was in the head of the first test of the Honda CB450 Black Bomber - with a capacity of 44 hp -: "Only suitable for very experienced motorcyclists with circuit experience".
In 1969, BMW presented the / 5 series of which the top model, the R 75 / 5, had a scientifically substantiated capacity of 50 hp. The BMW research scientists and technicians had seriously calculated that 50 hp rated it 
safe power for motorcycles on the public road.
A little later there was a cheering article in 'Motor' about the Guzzi 850 GT. That was the first machine to put a black line on the asphalt purely on couple. Thirty years later, when I found the number containing the test again, I clearly saw what I hadn't seen as a twelve-year-old: the black line on the asphalt was clearly drawn. A kind of photojopt o.1
In the meantime, you can just buy a road motor from 200 pk. And that thing is then loaded with electronic control cousins that must ensure that all that power is not immediately deadly for the driver.
The provisional highlight in these developments is the new Kawasaki H2R. You can see and hear that during the upcoming Motor Fair. The thing is pulled open on the test bench every afternoon and delivers 326 pk.
I read it and sigh. Stand up. Walk to the garage and beat my 50 horsepower on his tank. I address them calmly: “John, it's just like when you were created enormously. 40 Centimeter seems very impressive, but what can you do with it? "