Valves (intake and exhaust) for 125–150 cc 4-stroke scooters. They open and close the ports in the cylinder head: they let the mixture into the cylinder and release the exhaust gases.
Valves need replacing if they are burnt or have lost their seal: compression drops, the engine starts poorly and loses power. After replacing the valves, they must be lapped to the seats and the clearances set.
What to consider when choosing:
- valve diameters
- head type
- condition of the seats
