How does a YPVS valve work?

The YPVS employs a spiral shaped valve located on the top of the cylinder’s exhaust port. This valve is operated by means of a cable from a computerized mechanical control unit which detects the ignition frequency and determines the required turning angle of the valve. In this way the valve moves upward and downward out of the exhaust port.

Does a Yamaha YZ have a power valve?

The YZ series of motocross bikes has a mechanical power valve which is activated at RPM speed. The YPVS is only found on the liquid-cooled bikes not air cooled versions. Yamaha have also used a guillotine version in some of their later models such as the TZR250R SPR model.

Does Yamaha have a YPVS?

The YPVS is only found on the liquid-cooled bikes not air cooled versions. Yamaha have also used a guillotine version in some of their later models such as the TZR250R SPR model. Yamaha was actually the first company to produce consistent results with their YPVS in their race bikes.

What is a two-stroke power valve system?

The two-stroke power valve system is an improvement to a conventional two-stroke engine that gives a high power output over a wider RPM range.

What is a Yamaha FX Cruiser service manual?

Page 1 WaveRunner FX High Output FX Cruiser High Output SERVICE MANUAL *LIT186160283* LIT-18616-02-83 F1S-28197-1G-11... NOTICE This manual has been prepared by Yamaha primarily for use by Yamaha dealers and their trained mechanics when performing maintenance procedures and repairs to Yamaha equipment.

When did Yamaha start using YPVS?

The Kadenacy effect was harnessed and controlled to a point that gave Yamaha great advantage over all the other manufacturers throughout the late '70s and into the mid '80s. The first street bikes with YPVS were the RZ/RD350 YPVS (LC2-onwards), and RZ/RD500 GP Replica in 1983-84.