Camshaft and valves are part of a 4-stroke engine. The camshaft controls the opening and closing of the valves by converting the rotary motion from the engine into a longitudinal motion. The valve is responsible for supplying fresh and removing burnt gases. ... In general the intake valve separates the intake from the combustion chamber and the exhaust valve separates the combustion chamber from the exhaust. We stock camshafts and valves as well as accessories like timing chains, bearings for 50cc scooters with 4-stroke engine and maxi scooters. Manufacturers like Naraku are specializing in the 4-stroke market and offer a wide range of spare camshafts. Manufacturers like Malossi also offer tuning / sport camshafts with modified angles to optimize engine performance. Valves can also be optimized, e.g. with reinforced springs and valves with improved sealing properties and long service life.