The twin cylinder engine has potential for much more power.
Increasing the horsepower of your Harley Sportster 1200 involves trade-offs between performance and potential problems. Modifications bring no guarantee of usable additional performance. Harleys are fast bikes when they come from the factory, so the added expense and complexity may not be worthwhile. Despite these concerns, such modifications remain popular. Harley dealers sell many kinds of accessories along with mechanical services to install and tune the upgrades. Besides many after-market vendors, Harley-Davidson itself offers branded accessories designed to enhance the performance, look and sound of its products.
1. A new exhaust can add power and sound great.
Replace the exhaust system. By adding a higher flow exhaust system, any engine will experience improved performance. If the engine has to work less to push the exhaust gas out, it has more power to drive the rear wheel. Do your research and find an exhaust system that has been proven to increase your power.
2. Custom air filters can look great.
Replace the air filter with one that has more free flow. More air into the engine along with more gasoline will make for more horsepower. Make sure that the air filter you purchase meets the warranty requirements of Harley-Davidson. Too much flow can mean grit or water in your engine.
3. Adjust the fuel injection. With the change to the air filter and the exhaust system and the increased air flow, some changes to the fuel system will be required. Careful adjustment can yield benefits in additional power.
4. Performance tires are much softer than stock.
Swap out the tires. A stickier tire means better traction. Stock motorcycle tires are a compromise; a harder compound means they will last longer, but they will tend to slip more when the throttle is applied.