Most people don't realize that dyno's only measure torque...Hp is a mathematical equation...I always find it funny when someone quotes HP/torque numbers that are not possible, and anyone with a calculator can call BS.

FYI horsepower ratings are quickly becoming an "American" thing. Most of the rest of the world has dropped HP ratings on industrial engines and electric motors...they are rated in Kilowatts and even calories...but most cars are still rated in HP because it sounds "cool".

 

Someone in England in the 19th century decided 1 HP should be the amount of power/work it takes to lift 33,000lbs a distance of 1 foot vertically in a time period of 1 minute. - Google

Power is power no matter what units you measure it in.

1 HP = 0.745699872 kilowatts

 

That statement about the wall is an old method of teaching the differance between hp and torque and it is quite accurate but you have it wrong. When you are the pushing on the wall, you are the engine, not the rider. The rider is the wall, the object being pushed. Until the wall moves, it feels nothing, once it starts moving, it feels movement and acceration, or work being done. The engine can produce torque without moving, but once it moves any, even one rpm, it is producing power (work being done) that can be measured. You feel that power. As stated, if you have two bikes, both the same weight, and geared correctly (meaning you have a gearbox that can keep the engine in the part of the powerband where it is producing the most hp, not torque) and one has 150/75 hp/tq and the other has 75/150 hp/tq, the one with 150 hp will blister the one with 150 foot pounds of torque and you will certainly FEEL that difference in hp.

 

My last car was dynoed at 180whp and 240ft/lb. That just means it makes peak tq low in the HP range and can't sustain it at the higher end.

Post a dyno of the KZ1100cc vs. a bike that's putting out 150whp and 135ft/lb.

 

One problem is you can't get a narrow angle (45degree) VTwin to spin quickly because of the inherent issues with vibration. If you change the angle between the cylinders to 90 degrees then you get perfect first order harmonic balance and drastically reduce vibration but.......... you also loose the trademark HD look and sound, probably why HD have not already done this. This is one reason why Ducati can get twice the horsepower out of their 1200cc 90 degree VTwin as HD gets from their 1200cc 45 degree VTwin. Torque figures are similar.

The other issue that becomes a problem with higher speed operation is breathing. Getting fuel and air into the engine and exhaust out of it. A four valve per cyl engine will breath a lot better than a 2 valve per cyl. engine. Also the valve area/displacement ratio is another way to look at the same problem. A 1000cc 4 cyl. engine with 16valves is going to have a higher ratio and therefore breath better than a 1000cc 2 cyl. engine with 8 valves. This is why you see 8 and 10 cyl engines in formula one which has a 2400cc displacement limit.

Finally higher speed operation generates more heat which necessitates water cooling to maintain durability/longevity.