Special tools are used for disassembly and testing can only be carried out using a vacuum gauge. It is important to remember that failure of the device does not mean brake failure, but rather that the pressure on the foot brake pedal must be increased accordingly.
17.7.1. Checking the brake torque booster
Turn off the engine and press the brake pedal several times to remove all vacuum from the cylinder. It is easy to press the brake pedal and start the engine. If the vacuum system is working properly, the brake pedal will yield easily to foot pressure and only a small amount of pressure will be required to keep the pedal depressed.
If the brake pedal does not move, the brake torque booster is faulty. The next time you check, you need to pull the handbrake while releasing the brake pedal. Start the engine at high idle speed, turn off the ignition and immediately release the gas pedal. This creates a vacuum in the system. Wait at least 90 seconds with the engine still off and press the brake pedal. If vacuum support cannot be installed after the pedal has been depressed at least twice. there is a malfunction in the check valve.
17.7.2. Removing and installing the brake booster
Removing the brake booster is an extensive job because the steering shaft must be removed. These works are described in the relevant chapters. If the brake booster needs to be removed, it is necessary to connect the brake lines from the master cylinder, remove the vacuum hose and, after loosening the nuts, remove the master cylinder.
Disconnect the push rod from the brake pedal (remove the cotter pin and bolt) and release the brake booster mount. Remove the amplifier.
If necessary, unscrew the fork head after loosening the push rod nuts. The brake booster is installed in the reverse order of removal. Bleed the brake system as described above.
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