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Bleeding Your Brake Lines

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Bleeding Your Brake Lines

Regular maintenance of your Royal Star Venture includes replacing the brake fluid. Below are 2 methods for performing this "bleeding" operation. The first is the more conventional method while the second involves the use of a vacuum tool. Before you start, make sure you have a new container of DOT4 brake fluid.

WARNING - Brake fluid eats paint and must not come into contact with any part of your bike. You cannot clean it off fast enough to prevent damage. Protect your paint finishes with a damp cloth wherever there is a risk of spilling brake fluid onto it.

Before beginning, make sure the bike is secure and rotate the handle bars so the fluid reservoir is as near to horizontal as possible. Cover anything that could get brake fluid spilled on it. Remove the rubber caps from the bleeder valves and clean the valves. Note, while these procedures describe bleeding the front brakes, they also apply to the rear brake.

Method One

Place a clear plastic tube over the bleeder valve on the left caliper (farthest from reservoir) and place the other end into a jar.

Remove the screws that secure the master cylinder cover but leave the cover in place.

Assuming the system can create pressure, gently pull the brake lever and maintain this pressure while perfoming the next 2 steps. (you may need some help here)

Open the bleeder valve and allow 50% or more of the fluid in the reservoir to drain.

Close the bleeder valve (while fluid is still coming out) and before the reservoir is empty.

Release the lever with the reservoir cover still on. Fill the reservoir with new fluid and repeat the last 3 steps until the fluid runs out clean and clear.

Repeat this procedure for the right caliper.

Note: If you release the brake lever while the bleeder valve is open, or if you allow the reservoir to empty, you will introduce air into the system. This is not a good situation and you will have to repeat the procedure until all the air is gone.

Method Two

Using a tool called Mighty-Vac makes brake bleeding simple and clean. Mighty-Vac is a small vacuum pump that pulls the brake fluid through the brake line from the bleeder valve on the caliper and collects the excess fluid in a cup built into the tool. It comes with adapters and hoses included.

Remove the cap from the brake fluid reservoir and fill it with the proper fluid.

Connect the Mighty-Vac to the bleeder screw using the correct size adapters for your particular bike.

Pump the Might-Vac handle a few times to build up a vacuum.

Slowly open the bleeder valve and you'll see brake fluid flow through the hose. If you see air bubbles in the fluid, this is due to leakage around the valve and any air in the system. (you can seal air leaks around the valve with grease)

Continue pumping on the tool slowly until the fluid flows with no air in it.

Important Check the fluid reservoir and replace what you have drawn through the system while bleeding it.

Once the fluid flows through the hose with no air bubbles in it, close the bleeder valve, unhook the hose and replace the rubber cap.

When closing the valve, there must still be some vacuum present and the reservoir must not be empty.

Recheck the fluid reservoir, fill it to the proper level.

Wipe off the reservoir to make sure no dirt gets in the fluid and replace the cap.

Before you ride the bike, you must pump the lever and pedal to confirm that they are solid and not spongy.

Brake fluid absorbs moisture. This lowers the boiling point so that when the system is hot, gas forms in the lines. This will cause increased wear as the pistons can not release properly when gas or bubbles don't flow back into the fluid sump. Cool brake fluid may show no signs of contamination, but that does not mean that moisture has not entered the system.

The most important thing is to make sure you use the required DOT4 brake fluid. Mixing different brake fluids will destroy the seals and o-rings leading to a complete rebuild of the system.

Last update: 04:30 PM Sunday, September 26, 2004

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