Yamaha - Oil Tank Cap Assembly - 6H4-21770-01-00Yamaha Oil Tank Cap Assembly Lubrication System Component 6H4 21770 01 00 Overview Ive learned not to overlook something as simple as an oil tank cap, especially on older two stroke setups. A worn or loose cap can let air into the system or allow contamination, and thats where problems start. This updated version replaces the older one and gives you a better, more reliable seal. Its a small upgrade that helps keep your oil system doing its job without