A cammed motorcycle engine refers to an engine that has been modified with aftermarket performance camshafts or camshaft profiles. The term "cammed" is derived from the word "camshaft," which is a rotating component responsible for controlling the opening and closing of the engine's valves.
Here are the key differences between a cammed motorcycle engine and a regular motorcycle engine:
Camshaft Profile: The camshaft profile plays a crucial role in determining the timing and duration of valve opening and closing events in the engine's combustion cycle. In a cammed engine, aftermarket camshafts are typically installed with profiles that differ from the stock camshafts. These modified camshafts are designed to provide different valve lift, duration, and timing characteristics, with the aim of improving performance, power output, and torque across the engine's RPM range.
Valve Timing and Lift: By changing the camshaft profiles, a cammed engine can alter the valve timing and lift. This modification can result in increased valve lift, longer duration of valve opening, and modified valve overlap (the period when both the intake and exhaust valves are partially open at the same time). These changes can optimize airflow and combustion, potentially leading to improved power and performance.
Power and Performance: The primary goal of camming an engine is typically to enhance power and performance characteristics. By optimizing valve timing and lift, a cammed engine can improve volumetric efficiency, which refers to the engine's ability to ingest and expel air and fuel. This can result in increased horsepower and torque output, particularly at higher RPMs where improved breathing and enhanced airflow become more critical.
Idle and Low-End Characteristics: While a cammed engine can offer performance gains at high RPMs, it may also impact idle quality and low-end torque. Some aggressive camshaft profiles designed for high-performance applications can result in a rougher idle and reduced low-end torque compared to a stock engine. This trade-off is due to the modified valve timing and lift, which can affect low-speed engine behavior and responsiveness.
Fueling and Tuning: Modifying the camshafts in an engine often necessitates adjustments to the engine's fueling and tuning parameters. The increased airflow and changes in combustion characteristics may require recalibration of the fuel injection or carburetor settings to maintain proper air-fuel ratios. This tuning process is crucial for optimizing performance, ensuring reliability, and preventing issues such as poor fuel economy or engine damage.
It's important to note that camming an engine is a performance modification that may require additional upgrades or modifications to other components such as intake and exhaust systems, cylinder heads, and engine management systems to fully realize the benefits and maintain engine reliability. Professional expertise and proper tuning are highly recommended when modifying a motorcycle engine with aftermarket camshafts.