Suzuki GSX-R750, Service Manual

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4-20 FI SYSTEM AND INTAKE AIR SYSTEM
INTAKE AIR SYSTEM
SECONDARY THROTTLE CONTROL SYSTEM
The secondary throttle control system (STC system) consists of the secondary throttle valve (ST valve),
secondary throttle valve actuator (STV actuator) and ST valve control cables.
ST valve is installed in each throttle body. STV actuator is installed on the right side of the throttle body
assembly with the bracket. The ST valve is turned by the ST valve control cables.
This system is designed to control the volume and the velocity of intake air so as to improve engine output
power. The system produces more seamless and linear throttle response.
This is performed by opening or closing the throttle body intake port according to the gear positions and
engine rpm.
When the engine is running in a low speed range, the intake port is almost closed for controlled intake air
volume. This improves the effect to intake air flow pulsation so that the engine can output higher power in
this speed range.
As the engine speed grows faster, the intake port are gradually open for guiding the proper volume of air
into the throttle bodies so that the engine can produce the maximum power in each speed range.
Secondary throttle valve
Secondary throttle
valve actuator