What are the valves of a motorcycle and what does it do?

The valve stems of the motorcycle they are cylindrical in shape, and the reciprocating movement is carried out continuously in the valve passage, and their surface must be heat-treated and polished; The shape of the valve stem end depends on the fixed shape of the valve spring, the commonly used structure is two halves of the lock plate to fix the spring seat, the valve stem end has a groove ring to install the lock plate, some are fixed with a lock pin, and the end has a hole to install the lock pin.


Extended profile To improve the efficiency of intake and exhaust, now more use of multi-valve technology, multi-valve structure is easy to form a compact combustion chamber, centrally arranged injector, so that the oil mixture combustion and gas is faster, more uniform, the weight and opening of each valve are appropriately reduced, so that the valve opening or closing speed is faster. The valve head temperature is very high (inlet valve 570 ~ 670K, exhaust valve 1050 ~ 1200K), but it also bears the pressure of the gas, the force of the valve spring, and the inertia of the transmission component, its lubrication, cooling conditions are poor, requiring the valve to have a certain strength, rigidity, heat resistance and wear resistance. The intake valve is generally made of alloy steel (chromium steel, chrome nickel steel), and the exhaust valve is made of heat-resistant alloy (chromium silicon steel). Sometimes, to save heat resistant alloys, the exhaust valve head is made of heat resistant alloy, while the rod part is made of chrome steel, and then the two are welded together. The valve is divided into two parts: the valve head and the valve stem. The upper part of the rod is in contact with the rocker arm, and the semicircular arc connection is used between the valve stem and the head, which can reduce the resistance to gas flow and improve the strength of the valve. The valves rely on the conical surface of the head to seal the intake and exhaust vent, and the contact angle with the seat surface is generally 90° or 60° (the bevel angle is 45° and 30° respectively ). The inlet valve head diameter is larger than the exhaust valve, the purpose is to reduce intake resistance and increase intake volume.