Introduction

This guide will show you how to bleed and refill the front brake lines on the Harley-Davidson Sportster Evolution.

Parts

When working with the brake lines, we strongly recommend using a bike stand or similar apparatus to stand the bike upright and lock the front tire in place.
  • When working with the brake lines, we strongly recommend using a bike stand or similar apparatus to stand the bike upright and lock the front tire in place.

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Using a Phillips #2 screwdriver, remove the two screws securing the lid on the master brake fluid cylinder. Remove the lid from the master cylinder, and set it aside. Brake fluid is very caustic, and will easily strip paint and discolor chrome. Do your best to not spill any, and be ready with a damp rag in the event of a spill.
  • Using a Phillips #2 screwdriver, remove the two screws securing the lid on the master brake fluid cylinder.

  • Remove the lid from the master cylinder, and set it aside.

    • Brake fluid is very caustic, and will easily strip paint and discolor chrome. Do your best to not spill any, and be ready with a damp rag in the event of a spill.

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Locate the brake fluid bleed valve on the top of the front brake assembly, and flip up the rubber cap covering it. Slide a 3/8" brake bleeder hose over the bleed valve. If you are using a stop valve for bleeding the brake lines, make sure that the arrow on the valve is pointing away from the brake assembly (along the direction of flow).
  • Locate the brake fluid bleed valve on the top of the front brake assembly, and flip up the rubber cap covering it.

  • Slide a 3/8" brake bleeder hose over the bleed valve.

    • If you are using a stop valve for bleeding the brake lines, make sure that the arrow on the valve is pointing away from the brake assembly (along the direction of flow).

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Make sure that the free end of the bleed tube is safely pointed at some kind of reservoir. A glass bottle works great. Bleeding the brake lines is a whole-body effort. You will need to use one hand to pump the brake handle and one hand to maneuver a wrench on the brake bleed valve.
  • Make sure that the free end of the bleed tube is safely pointed at some kind of reservoir. A glass bottle works great.

  • Bleeding the brake lines is a whole-body effort. You will need to use one hand to pump the brake handle and one hand to maneuver a wrench on the brake bleed valve.

    • You may need to raise or lower your bike stand to be able to reach all the way across the bike.

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Before proceeding, read all the way through steps five and six to make sure that you completely understand the actions for bleeding the brake lines. Carefully pump the brake lever a few times to build up pressure in the brake lines. In the next step, you will release the fluid from the brake lines by opening the bleed valve at the bottom of the lines and simultaneously squeezing the brake lever.
  • Before proceeding, read all the way through steps five and six to make sure that you completely understand the actions for bleeding the brake lines.

  • Carefully pump the brake lever a few times to build up pressure in the brake lines.

  • In the next step, you will release the fluid from the brake lines by opening the bleed valve at the bottom of the lines and simultaneously squeezing the brake lever.

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Using a 3/8" wrench with your left hand, open the bleed valve on the front brake cylinder. The built-up pressure in the lines will force some of the brake fluid out of the lines. Continue to force more brake fluid out of the brake lines by depressing the front brake lever with your right hand.
  • Using a 3/8" wrench with your left hand, open the bleed valve on the front brake cylinder.

    • The built-up pressure in the lines will force some of the brake fluid out of the lines.

  • Continue to force more brake fluid out of the brake lines by depressing the front brake lever with your right hand.

    • While bleeding the brakes, focus on the bleeder hose. If you see an air bubble traveling up the bleed hose, close the bleed valve immediately, and begin the process again.

  • Once the brake lever is completely depressed, quickly close the bleed valve, making sure that no air bubbles enter into the brake lines.

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Repeat the process outlined in step five and six until the amount of brake fluid in the master cylinder is getting low. Make sure to not remove so much brake fluid that air gets into the brake lines. Refill the master cylinder with fresh brake fluid until the level of fluid is even with the metal protrusion in the rear right corner of the master cylinder.
  • Repeat the process outlined in step five and six until the amount of brake fluid in the master cylinder is getting low.

    • Make sure to not remove so much brake fluid that air gets into the brake lines.

  • Refill the master cylinder with fresh brake fluid until the level of fluid is even with the metal protrusion in the rear right corner of the master cylinder.

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Continue flushing the brake lines as described above until you see the new brake fluid coming through the bleed tube. The new brake fluid will be a lighter color than the old, discolored brake fluid. Keep an eye on the master cylinder. If the fluid level gets too low again, be sure to add more fluid.
  • Continue flushing the brake lines as described above until you see the new brake fluid coming through the bleed tube.

    • The new brake fluid will be a lighter color than the old, discolored brake fluid.

  • Keep an eye on the master cylinder. If the fluid level gets too low again, be sure to add more fluid.

  • When you are seeing new brake fluid coming through the bleed hose, stop the flushing process and firmly close the bleed valve.

  • Gently pull the bleed tube off of the bleed valve and re-cover the valve with the little rubber cap.

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Fill the master brake cylinder one last time with fresh brake fluid until the fluid is level with the metal tab in the rear right corner of the cylinder. Fill the master brake cylinder one last time with fresh brake fluid until the fluid is level with the metal tab in the rear right corner of the cylinder.
  • Fill the master brake cylinder one last time with fresh brake fluid until the fluid is level with the metal tab in the rear right corner of the cylinder.

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Using a damp rag, wipe down the rim and rubber gasket of the master cylinder and the master cylinder cover. Using a damp rag, wipe down the rim and rubber gasket of the master cylinder and the master cylinder cover.
  • Using a damp rag, wipe down the rim and rubber gasket of the master cylinder and the master cylinder cover.

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Using a Phillips #2 screwdriver, replace the master cylinder cover and screw it firmly into place. Using a Phillips #2 screwdriver, replace the master cylinder cover and screw it firmly into place.
  • Using a Phillips #2 screwdriver, replace the master cylinder cover and screw it firmly into place.

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Finish Line

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Brett Hartt

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2 Comments

Make sure you use the correct type brake fluid. A common issue especially with DOT5 is after bleeding the lever may not compress to activate the brakes. This is air in the fluid. DOT4 holds air as visible bubbles, while DOT5 holds air in microscopic bubbles. DOT4 holds water in suspension, while water in DOT5 will settle to the lowest part of the system usually in the calipers, which is why it is important to keep DOT5 systems bled. The cure for suspended air in DOT5 when renewing fluid is to squeeze the lever or pedal with the bleed valve closed, slipping your fingers off the lever releasing it rapidly with the master reservoir cap off. Notice if tiny bubbles come up into the reservoir. Also use a syringe with fluid attached to open bleed valve and force fresh fluid up into the system. With this technique you should be able to get some resistant pressure at the lever.

dkshaman - Reply

Then compress lever against this pressure, tie off and leave overnight. The pressure induced into the system will force held air out of the fluid. Repeat until lever or pedal feels firm at outer reach of adjustment.

dkshaman - Reply

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