The brake system may be the most important safety feature on a motorcycle.
One of the first customizations many riders make to their Harley-Davidson motorcycle is changing the handlebars. It sounds pretty simple at first–unbolt the old ones, then transfer over the old parts to the new one. However, if the brake line is too short, it impedes your range of motion and becomes a safety hazard. If it is too long, it may scratch and damage your motorcycle. Fortunately, replacing the brake line is fairly easy and can be completed just about anywhere with some simple tools.
1. Move your motorcycle to a clean, level surface. Place your motorcycle in first gear to prevent accidental movement. Place the run/off switch to “off.” Consult your owner’s manual and follow the instructions to disconnect your negative battery terminal.
2. Drain the fluid from your front brakes. First, cover your painted surfaces with shop towels to prevent damage from brake fluid or loose parts. Connect tubing to the bleeder valve located on your brake caliper. Run the tubing to a clean bucket. Using the adjustable wrench, open the bleeder valve–only one half to one turn should be enough. With the motorcycle upright, use the Phillips screwdriver to unscrew the master cylinder cover on your front brakes. Pump the brake lever and fluid should begin to flow. When the fluid stops flowing loosely, disconnect the tubing and move out of the way. Reinstall the master cylinder cover. Clean up any spilled fluid with shop towels.
3. Note the routing of the current brake line to ensure reinstallation follows the same pattern. Also, note the order of the mounting hardware where the brake line fits to the caliper and master cylinder. Using an Allen wrench, remove the brake line mounting clamps from the motorcycle. With the socket and socket wrench, remove the brake line from the master cylinder and caliper.
4. Replace the gaskets and connect the brake line fitting of the new brake line to the master cylinder. Replace the gaskets and connect the brake line fitting to the caliper. Consult your notes to ensure the line and fitting are at the proper angle and that the hardware was installed in the proper order.
5. Run the brake line through the mounting clamps and reinstall them on the motorcycle. Consult your notes to ensure the line is properly routed. Check the range of motion of your new brake line.
6. Reconnect the tubing and bucket to the caliper drain valve (it still should be open). Remove the master cylinder cover. Slowly add brake fluid until it begins to flow into the bucket. At this time, close the drain valve. Pump the front brakes several times and slowly add more fluid. Open the bleeder valve one half turn and bleed out any air in the line. Repeat until the master cylinder is full and no air bubbles are in the line. Replace the master cylinder cover. Dispose of used fluid in accordance with local laws.