Yamaha Technology in 80's : YPVS , What is this?
Effective control of the exhaust schedule
This YPVS system controls the exhaust gas time via a variable valve, so that the more efficient schedule can be guaranteed according to the speed, so that a higher power is reached.
Port synchronization (entry, exhaust and cleaning) is a very important factor that determines the characteristics of a 2-stroke engine. In general, the rapid timing of exhaust gases means that the engine works well in the high-speed and high-power range, while slow timing means the engine has good low-end torque.
However, a road racer or motocrosser, who must perform well, especially in the high performance range, also encounters many other situations, such as a turn, when he needs a high torque and good performance in mid-range, The YPVS meets both needs.
The YPVS uses a spiral valve on top of the cylinder exhaust connector. This valve is operated by a cable from a computer-assisted mechanical control unit, which detects the ignition frequency and determines the required rotational angle of the valve. This way, the valve moves up and down the exhaust connector. This means that the exhaust time is constantly adjusted to the speed level, allowing for more efficient timing across the entire speed range.
The TZ production driver has a mechanical control system, but the Racer YZR500 Factory, the first Yamaha machine to use the YPVS, has an electrical control system to adjust the exhaust time with an ignition pulse, like most sports bikes today.
Starting in 1980, TZ production pilots had a purely mechanical system, powered by the crank shaft. In 1983 came the switch to electronics, with the GP factory rider YZR500 and also the production machines RD250LC and RD350LC, which now also took over the power valve system immediately in the electronic version. At 350cc, performance with this technology has increased from 50 to 60 hp compared to the previous model!
Results
A more efficient exhaust schedule is provided throughout the speed range, combining both high performance and good fuel consumption.
This YPVS system controls the exhaust gas time via a variable valve, so that the more efficient schedule can be guaranteed according to the speed, so that a higher power is reached.
Port synchronization (entry, exhaust and cleaning) is a very important factor that determines the characteristics of a 2-stroke engine. In general, the rapid timing of exhaust gases means that the engine works well in the high-speed and high-power range, while slow timing means the engine has good low-end torque.
However, a road racer or motocrosser, who must perform well, especially in the high performance range, also encounters many other situations, such as a turn, when he needs a high torque and good performance in mid-range, The YPVS meets both needs.
The YPVS uses a spiral valve on top of the cylinder exhaust connector. This valve is operated by a cable from a computer-assisted mechanical control unit, which detects the ignition frequency and determines the required rotational angle of the valve. This way, the valve moves up and down the exhaust connector. This means that the exhaust time is constantly adjusted to the speed level, allowing for more efficient timing across the entire speed range.
The TZ production driver has a mechanical control system, but the Racer YZR500 Factory, the first Yamaha machine to use the YPVS, has an electrical control system to adjust the exhaust time with an ignition pulse, like most sports bikes today.
Starting in 1980, TZ production pilots had a purely mechanical system, powered by the crank shaft. In 1983 came the switch to electronics, with the GP factory rider YZR500 and also the production machines RD250LC and RD350LC, which now also took over the power valve system immediately in the electronic version. At 350cc, performance with this technology has increased from 50 to 60 hp compared to the previous model!
Results
A more efficient exhaust schedule is provided throughout the speed range, combining both high performance and good fuel consumption.