Phazer Knock Control System (KCS)

The new Yamaha Genesis 80 FI 4-stroke found in the all-new 2007 Phazer models produces a claimed 80 HP! How is this possible, from a 4-stroke of only 500cc? One of the ways is with high compression (12.4:1), high RPM (11,250 RPM) and a knock sensor – the Phazer Knock Control System (KCS).

Yamaha tells us the engine makes its rated 80 HP when using the recommended hi-octane fuel (premium) but that you can use 87-octane fuel, as the KCS system will automatically detect the lower octane fuel (via knock) and adjust the ignition timing accordingly. This will result in a loss of 4 HP without engine damage and without the KCS light coming on.

During prototype testing of the Phazer, Yamaha ran the system for over 4,000 miles on 87-octane fuel (before the oil cooler was added, no less) and the engine remained within specification after tear-down inspection. The KCS system is designed so that the Phazer models can be used on 87-octane fuel, assuming the proper gearing and clutching calibrations for the elevation of operation. If the KCS light comes on, consider the fuel source or the riding conditions (wet, heavy snow) or the transmission calibration (heavy flyweights, tall gearing).

If the KCS light flashes, this indicates a more severe knock condition and ignition timing adjustment. The light will continue to flash until the key is turned off to make sure the operator sees it. If this conditions repeats, engine speed will be limited to approximately 6,000 RPM. You should stop the engine, let it cool sufficiently, and make every attempt to replace the fuel with higher quality fuel and make the appropriate calibration changes, if required.

Most of the time, the light will never come on or flash at all. The system is intended to be a reliability safeguard and fuel switch, all automatically and seamlessly.