Overdrive simplified - And Suzuki GS150R - The only bike in India with this feature.

Overdrive can be also called as the highest gear in the transmission of a motor vehicle that is very much needed at high speeds and also for cruising purposes, which maximizes fuel economy and reduces the stress caused to the engine. It is an amazing mechanism in transmission that prevents deterioration of engine due to prolonged stress and high speeds while cruising  for a long time on the highways.

YRCS in Yamaha FZ, FZ-S & Fazer - Explained

The YRCS - Yamaha Ram air Cooling System is a new kind of feature which aids for better cooling in air cooled engines used in Yamaha's latest series of bikes in India the FZ, FZ-S and Fazer. This concept is quite simple and an innovative one. The additional attachment of a hood shaped tapered design placed at the cooling fin area of the engine projects the oncoming air flow while riding to the spark plug area where the temperature often rises to the peak. It also helps in better heat dissipation like a heat sink since it provides more surface area as far as I know. This set up along with front placed air flow shrouds directs the air flow perfectly to cool the engine fins.