Big horsepower numbers always look impressive on paper, but they don't necessarily indicate the best performance for a particular application. A 12-inch stretched Hayabusa with 400 turboed horsepower will work flawlessly at the strip, but on a twisty bit of road or track it'll likely be left in the dust by a 600cc sportbike with a squirt of nitrous-application is as important as the cold, hard numbers. SSB examines the various potent possibilities for making your ride rip.
Pipe, air filter and fuel-management system
In the truest sense of a bolt-on power adder, a full exhaust system, air filter and fuel-management box (or a jet kit back in the day for carbs) have been the standard go-to mods for nearly every ride on the road. Better looks, lighter weight and increased power are the benefits, and there isn't much more that needs to be done after installation.
The reason a freer-flowing exhaust gains power is because it eliminates the noise- and emissions-reducing muffler (that also is quite heavy) and allows the engine to move more spent gas quicker. The accompanying fuel-management box provides the necessary adjustment to the fuel injectors and airflow to work with the freer-flowing exhaust as well as the improved intake airflow from the aftermarket air filter.
The Holy Trinity of bike tuning:...
The Holy Trinity of bike tuning: pipe, air filter and fuel management.
A custom dyno tune is always beneficial, but a lot of the downloadable preprogrammed maps will suffice and help achieve power gains if dyno tuning isn't available or in the budget.
Power delivery is most noticeable with improvements in the midrange and top end. Gains range from 5-15 horsepower generally.
Best Application: Street rider desiring better looks, sound and performance.
Average expense: About $1500 for parts.
Housed inside this bottle...
Housed inside this bottle are ravenous horses that are unleashed at the push of a button.
Nitrous system
Nitrous is a highly debated mod because when improperly installed it can end in catastrophe, and stock engine components won't tolerate the increased heat of an extended nitrous spray for very long. This makes it ideal for delivery in quick bursts or only during full throttle (like during a quarter-mile run).
Essentially, a nitrous system adds a highly combustible gas (nitrous oxide) into the combustion chamber with more fuel and air to produce more power.
Power delivery typically comes as an instant rush at the press of a button or upon reaching full throttle (depending on set-up). Gains typically range from 20-80 horsepower.
Best Application: Street rider desiring increased performance and the dragstrip enthusiast.
Average expense: $1000 for parts and installation.
Engine internals
Engine internals aren't something that a "do-it-yourselfer" will be able to manage in his garage-only a qualified engine builder should be consulted. The range of tuning is vast, and can be as minor as a ported head to a big-bore kit (making the actual cylinder heads larger to host larger pistons).
According to Yamaha tuner Chuck Graves: "Modifying an engine for more power is all about optimizing pressure, and an engine can be thought of like a pump. During peak power the pressure and leverage on the connecting rods needs to be optimized. The length of the stroke, the shape and size of the combustion chamber and the shape of the piston all determine how well the 'bang' is utilized. Of course, valves and ignition timing come into play as well, but each component needs to complement the other for maximum efficiency and power.
"Newer sportbike cylinder heads and valves are excellent, and a port job and valves won't offer gains like it used to. For big power the old saying still applies-there's no replacement for displacement."