Not long ago a conversation stunned me, stopped me in my tracks. The person I was trying to help said, "There can't be anything wrong with my engine, it makes X horsepower on the dyno." This person was seeking help in resolving poor low speed and midrange performance. He had already admitted his engine had lower than normal cylinder compression. And I was getting ready to tell him that particular engine family has a very well deserved reputation for having extreme valve wear issues. And that since he had just had a big bore job done on it, the chances were pretty good the work was not done very professionally.
What is wrong with people? When did big numbers on a dyno trump real-world civility, driveability, throttle response, and ease of starting and warmup? Why is it so many worship at the altar of bragging rights while riding cantankerous, poorly set up and maintained, badly modified motorcycles? I am continuously perplexed by this.
Dynos are great, don't get me wrong. While wrenching for a well-known speed shop in the 1990s I amassed between 500 and 1000 hours of time in the dyno room, fettling a slew of CBXs, ZX11s, and even some fairly knarly Harley-Davidsons. But one thing everyone experienced with a dyno learns sooner or later, is that the more success with big numbers, through carburetor and ignition and air filter tweaks, the less streetable, the less rideable in everyday street conditions, the outcome is likely to be. Not always. The Harleys stayed pretty streetable, for sure. And even many sport bikes retained good street manners. But the focus on a "dyno-tuned" (that is, a bike subjected to adjustments that yield the most power on a dyno) streetbike has to be, is it still fun to ride in normal conditions? And more importantly, in the quest for power, has good mechanics, best practices, common sense even, been overshadowed? Too often it is.
For example, most bikes can be tweaked to yield a highest number through the expedient of leanning out the main jet. But is this good for the street? No, it isn't. The bike show markedly increased sensitivity to atmospheric conditions and other variables, basically falling on its face in all but the same exact conditions as those on the day it was "tuned." Similarly, the installation of a gauze type air filter or even naked intake horns, while "sexy" and promising satisfying power increases, their actual results really are almost too small to account for, and worse, they come at the price of greatly increased engine wear. Then there are the bags of cash that go into putting on exotic aftermarket carburetors, only to find that the bike has lost all its low speed manners. I call this so-called "high performance" done in low performance ways. And what about the things so many overlook? The mis-timed ignition? Those awful automotive ignition wires? Or the drive chain that shows kinking from lack of maintenance? Or the brakes whose fluid has promoted corrosion that has begun to seize up their calipers? The steering bearings badly in need of service? Even dangerously low tire pressures? These are all-too common on machines whose owners have spent tons of money and time chasing that last 1/2 horsepower, and yet have no time for those insignificant things that actually make the bike better.
There is performance and there is performance. The former is demonstrated on the dyno. Bragging rights. But the latter is far more important if you actually do more with the bike than trailer it around from meet to meet. Throttle response. Good pull (acceleration). Smooth throttle transition. Easy starting. Good behavior in stop and go traffic. No smoking or popping on decel. No rattling clutch at idle. These are things that the dyno can't help you with, but are way more important because they mean the difference between riding the bike often, and due to its idiosycrasies riding it less and less. Real performance means making the bike easy to live with, more than and in addition to, making it better peforming.