How to Add Horsepower to a VTX 1800by Troy Lambert
The Honda VTX 1800 is a fast bike, but it could use a little more horsepower. There are four basic ways to increase its performance and enhance your motorcycling experience. While adding horsepower to the VTX, you may also increase emissions, both noise and environmental. Many states have laws about what modifications are street-legal so check your local regulations before embarking on this project.
Modify or replace the stock intake system. Primarily to control emissions and improve fuel economy, the air intake system on most motorcycles is restricted by the factory. Opening it up and letting it breathe is one of the quickest and least expensive ways to improve horsepower. From replacing your stock filter with a high flow filter, such as those made by K&N, or a full intake, such as those from Kuryakan or Forcewinder, there are intake modifications for every taste and budget. Determine your needs, budget and desired outcome before purchasing a system.
Replace the stock exhaust system. Once the intake is opened up, you can only gain so much horsepower without letting the system breathe on the other end as well. There are a variety of exhaust systems available, from Cobra to Big Shot and everything in between. The more you let the intake breathe, the more you need to let the exhaust breathe as well. Often average performance statistics are available online for various systems. Because exhaust style and baffles affect noise, be sure to check, before purchasing a system, to make sure noise output will not exceed your local noise ordinances.
Modify the fuel injection programming. There are many options for this as well and many price ranges. However, quality and name are important in this category. Power Commander and B&B Computer are both trusted names in fuel management control for Honda. These systems help your stock fuel injection system cope with the increased airflow created in your previous two modifications. Most include a program to let you modify fuel system "maps," using your laptop or personal computer; but if you have gone this far in the process, it makes sense to purchase some dyno time at a local speed shop and use true data, not how the bike sounds or feels, to optimally map your fuel system. Remember that fuel system mapping affects your environmental emissions so be sure modifications do not violate local ordinances.
Upgrade the engine. This is the most costly and time-consuming step of the process; but if intake, exhaust and fuel management just haven't brought you quite as far as you want to go, engine modifications are the next step. Do it yourself with big bore kits from manufacturers such as Wiseco, available in a variety of configurations, or send your engine to an engine builder, such as Patrick Racing, for modifications. Local "speed shops" or machine shops often do custom engine modifications as well. Either way, you are sure to be satisfied by the maximum horsepower and performance you can get from your machine.
Things You'll Need
- Intake kit
- Exhaust kit
- Fuel remapping module
- Engine kit
- Local ordinances and emissions standards often require that motorcycles modified from stock be designated for off-road use only, and manufacturers will often sell you parts with a "track use only" specification. if you operate a motorcycle with off-road parts, you agree that the manufacturers and installers of these parts are not responsible for any fines you may incur from state or local law enforcement. Often fuel maps can be modified for street or track use, and can be easily "swapped" using a computer. Check your local ordinances and be informed before you make any modification to your bike.
Based in North Idaho, Troy Lambert has been writing how-to pieces and historical articles for magazines such as "Woodworking" and "Outdoor Idaho" since 1994. Lambert is also a novelist and has a diverse technical and philosophical education. He holds a technical certification from the Motorcycle Mechanics Institute in Phoenix.