Ycc-T (Yamaha Chip Controlled Throttle)/Ycc-I (Yamaha Chip Controlled Intake) - Yamaha Vmax VMX17C 2009 Service Manual

EAS2S31089
YCC-T (YAMAHA CHIP CONTROLLED THROTTLE)/YCC-I (YAMAHA CHIP CONTROLLED
INTAKE)
Mechanism characteristics
Yamaha developed the YCC-T and YCC-I system employing the most advanced electronic control
technologies. Electronic control throttle systems have been used on automobiles, but Yamaha has de-
veloped a faster, more compact system specifically for the needs of a sports motorcycle. The Yamaha-
developed system has a high-speed calculating capacity that produces computations of running con-
ditions every 1/1000th of a second.
The YCC-T system is designed to respond to the throttle action of the rider by having the ECU instan-
taneously calculate the ideal throttle valve opening and generate signals to operate the motor-driven
throttle valves and thus actively control the intake air volume.
The ECU contains three CPUs with a capacity about five times that of conventional units, making it pos-
sible for the system to respond extremely quickly to the slightest adjustments made by the rider. In par-
ticular, optimized control of the throttle valve opening provides the optimum volume of intake air for
easy-to-use torque, even in a high-revving engine.
The YCC-I system calculates the throttle values from the engine speed, activates the intake air funnels
with the electronic control motor drive to control the intake pipe length in order to gain the high power
output in all revolution ranges from low speeds to high speeds.
Aims and advantages of using YCC-T system
• Increased engine power
By shortening the air intake path, higher engine speed is possible → Increased engine power.
• Improved driveability
Air intake volume is controlled according to the operating conditions → Improved throttle response to
meet engine requirement.
Driving force is controlled at the optimal level according to the transmission gear position and engine
speed → Improved throttle control.
• Engine braking control
Due to the throttle control, optimal engine braking is made possible.
• Simplified idle speed control (ISC) mechanism
The bypass mechanism and ISC actuator are eliminated → A simple mechanism is used to maintain
a steady idle speed.
• Reduced weight
Compared to using a sub-throttle mechanism, weight is reduced.
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3
1. Accelerator position sensor
2. Throttle position sensor
3. Throttle servo motor
4. Throttle valves
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1-22
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2
3
4
FEATURES
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