Motorcycle Camshafts & Components

Camshafts are some of the most important components of your motorcycle’s engine. Inboard cams regulate the work of its valves by moving pushrods and activating rockers so that the valves can open at the right time and stay open for the right period. Overhead cams are installed over the valves and push them directly in the cylinder head. This eliminates the need for additional moving parts in the forms of pushrods and rocker arms thus making it easier to achieve higher revolutions and produce more power. The operation of the motor largely depends on how far the valves are lifted, so the installation of an improved camshaft is a great way to start modifying your engine.

Before trying to get more power from the motor, you should use all of the available bolt-on upgrades, such as larger exhaust, high-performance air cleaner, and fine-tuned fuel delivery system. The right aftermarket camshaft can make your powerplant produce more torque while operating more efficiently. Depending on your riding style, you may choose the camshaft that provides more power in low rev range, which is great if you want to feel more confident while cruising on city streets, or opt for parts that allow for more torque on higher revolutions, which is useful if you tend to ride long distances on interstate highways.

To ensure correct timing, the camshaft must be rotating in sync with the engine’s crankshaft, which is why both these shafts are linked with a timing chain or cog belt. In all four-stroke engines, to complete one cycle, the camshaft must rotate once, while the crankshaft makes two complete revolutions, which is why the camshaft pinion gear or sprocket always has twice as many teeth as the crank gear or sprocket. A single overhead cam (SOHC) configuration includes one cam that operates both intake and exhaust valves via rockers. A double overhead camshaft (DOHC) configuration means that one shaft opens intake valves and another controls exhaust ones.

The DOHC version of the camshaft utilizes the direct actuation of the valves which allows for higher engine revolutions. That is why this layout is most often used in sportbikes. To choose the right aftermarket camshaft that fits your engine and riding style, you have to know three main specifications: lift, duration, and intake closing time. Lift defines how far the valve moves from its seat when it is opened. The farther the valve goes, the quicker the air-and-fuel mixture can enter and exhaust gases can escape the cylinder. It means that more fuel can be burned in the combustion chamber thus increasing the output of the engine.

The valve opening has its limits. Stock valve springs cannot be compressed more than they were designed to, so you might have to invest in performance springs. Note that to install new springs, you will have to remove the cylinder head. The downside of the high lift camshaft is its accelerated wear and increased valvetrain noise, which is especially undesirable in long-distance travel applications. The duration of the valve opening is measured in degrees of camshaft rotation. If you want to increase the horsepower of your engine on higher RPMs, consider installing a cam with later intake closing time. It is most suitable for larger, high-compression motors. Lower-compression engines work better with cams offering short intake duration and early intake closing time.