If your Yamaha FZ 16 is accelerating automatically when you start the bike, and there is no issue with the throttle cable, there could be a few possible causes:
Idle Speed Adjustment: The automatic acceleration could be due to an incorrect idle speed setting. The idle speed is the engine speed when the bike is at rest. If the idle speed is set too high, it can cause the bike to accelerate on its own. Adjusting the idle speed to the manufacturer's recommended specifications should resolve this issue.
Air Intake System: Another possibility is that there is an issue with the air intake system, such as a clogged or sticking throttle body or a malfunctioning idle control valve. These components play a role in controlling the air-fuel mixture and idle speed. If they are not functioning correctly, it can cause unintended acceleration. Cleaning or repairing these components may be necessary to resolve the issue.
Fuel System Issues: Problems with the fuel system, such as a malfunctioning fuel injector or a blocked fuel line, can disrupt the proper fuel delivery and cause erratic engine behavior, including automatic acceleration. Ensuring the fuel system is clean and functioning correctly can help resolve this issue.
Engine Management System: The electronic engine management system, including sensors and the engine control unit (ECU), plays a crucial role in regulating the engine's performance. If there is a fault or malfunction in the system, it can cause unexpected acceleration. A diagnostic scan by a qualified technician can help identify any issues with the engine management system.
It's important to have a qualified mechanic or Yamaha service center inspect and diagnose the issue with your Yamaha FZ 16. They will have the expertise and necessary tools to pinpoint the exact cause of the automatic acceleration and provide an appropriate solution.