Kuryakyn Hyper-Chargers

Now here is an interesting item. It is possibly the most popular aftermarket product for sale, and yet could be the cause of a lot of the problems I have been hearing about.

Let's start with something you might not have noticed. One of the most attractive things about the Hyper-Charger are those cute little butterflies that flutter open and closed when you work the throttle. It's so cool, just like the blowers on the top fuel funny cars... except for one thing, the Hyper-Charger butterflies operate off manifold vacuum and the top fuelers are operated mechanically by the throttle linkage.
At idle and normal cruising speeds, the main air intake is through the open butterflies, but when you accelerate, opening the carburetor or throttle body butterfly - the manifold vacuum drops causing the Hyper-Charger's butterflies to close. Now the main air intake is shut off by the closed butterflies so there has to be another air intake area, and you will see a slot at the bottom rear of the Hyper-Charger body for this purpose.

Kuryakyn claims that installing this air cleaner kit will improve performance and horsepower and that is true... under the right conditions. The reason it improves performance is because it utilizes a K&N free-flowing style filter, the same as you will find in the Screaming Eagle air cleaner kit and many others, even S&S is using the K&N style filter now. What the company does not tell you is that it will produce much better results on the dyno than on the highway. On the dyno it works great, but the dyno won't reproduce that 80mph wind forced into this air cleaner and out the rear like you get on the highway.
Because of the way the air travels into the front and out the rear of the Hyper-Charger, instead of forcing air into the carburetor, it actually pulls or "siphons" air (and fuel) out. As a result, you get what has been described as a "dead spot" or lack of power at highway speeds, not to mention the fuel breaks down the oil in your air filter hampering it's usefulness and the fuel mixed with air filter oil tends to deposit itself all over the right side of your bike when you go on long rides and then when you stop it all drips down on the cam cover, your foot, that cigarette butt you just dropped, and so on...