How To Get Air Out Of Your Dirt Bike Brake Lines

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If your brakes are feeling kind of spongy chances are your brake lines are full of air. The solution to this is bleeding your brakes and in this post, I’ll be showing you how to bleed them and also change the brake fluid in your dirt bike.

It might seem like an intimidating task to change your brake fluid but it’s actually pretty straightforward and is something you should do regularly on your dirt bike. You’ll know it’s time to get it done when your brakes start to feel spongy rather than springy and responsive.

Just like engine or transmission oil, they don’t last forever and as they do their job they start to deteriorate and break down. All you’ll need to get the job done is a screwdriver, a wrench, a drip pan, and of course, brake fluid.

How To Bleed Brakes On Your Dirt Bike

I always like to wash my bike before I start any sort of work like this because if you get any dirt or debris inside it, it’ll be no good at all. After it’s all nice and clean you’re ready to get started!

  1. The first thing you’ll want to do is find the main reservoir (which is on the handlebars by your front brake) and remove the top cap of it. Once that’s off you’ll want to fill it with brake fluid (it’ll tell you what kind of the cap itself).
  2. After that, you’ll want to find the drainage nut on the back of the brake caliper (take the rubber cap off first). Put some sort of drip pan below it to catch all the fluid that will be coming out. You can also attach a hose if you prefer that.
  3. Give the brake lever a few pulls, hold the lever down, and slowly loosen the drainage nut. The fluid will start coming out and your lever will get really soft. Tighten the nut back up and let go of the lever. All you have to do now is repeat this process until you start seeing the new fluid come out (make sure you keep topping up the reservoir so it doesn’t go dry).
  4. Once you see the new fluid coming out simply tighten the drainage nut, replace the rubber cap that goes on it, top up the main reservoir to the correct spot (it should give you a line), and put the cap back on.

That’s pretty much it. You can hold the brake lever down for a few hours using some zip ties and after that, you should be good to go and your brakes should be as good as new.

How To Reverse Bleed Dirt Bike Brakes

This is a different way to bleed your brakes and instead of pushing brake fluid from the top you’ll push it through the bottom and out the top. This can sometimes work better because it doesn’t allow any air into the system. If you’ve tried the normal way to bleed brakes and it’s still spongy I’d recommend you give this a try.

You’re going to need 2 syringes to do this. One for pushing the brake fluid in and another one for taking the brake fluid out of the main reservoir. Here’s how you do it:

  1. The first thing you’ll want to do is remove the main reservoir cover (by the front brake lever). Make sure the bike is level so the fluid doesn’t spill out and make sure you don’t get any fluid on your skin or parts of your bike.
  2. The next thing you’ll want to do is remove the brake fluid that’s in the reservoir with one of your syringes.
  3. Remove the drainage cap that’s on the back of the brake caliper so you can access the drainage nut.
  4. Fill your syringe with new brake fluid and attach the hose to the drainage nut. The hose may pop off while you’re putting the fluid in so you can secure it with a zip tie.
  5. Loosen the drainage nut with your wrench and slowly start inserting the new brake fluid. Once you’ve put a small amount of fluid in, tighten the nut back up and check the main reservoir to make sure it’s not full.
  6. Empty the reservoir again with your syringe and repeat the process until all the old fluid is out and your brake lever is no longer spongy.

That’s pretty much it. Make sure you tighten the drainage nut and then you can remove the hose and put the drainage cap back on. Make sure the correct amount of fluid is in the reservoir (there should be a line) and put the main cap back on. Make sure your brake feels solid and you’re ready to go!

Can You Use Car Brake Fluid In A Dirt Bike?

You can use car brake fluid in your dirt bike but I’d recommend against it. Most cars use Dot 3 brake fluid while most dirt bikes use Dot 4. If you use Dot 3 brake fluid in your bike it’ll most likely boil faster and that’s not going to be good for your bike. Don’t be lazy and just use the stuff that’s recommended and you’ll have a lot fewer problems.

Dirt Bike Brake Bleeding Tips

Here are just some additional tips for when you bleed your dirt bike brakes:

  • When you’re adding brake fluid to your bike make sure it’s standing upright so you get a true reading on how much fluid is in your bike.
  • When inserting the new brake fluid from the bottom make sure you hold the syringe upright so air doesn’t form inside the hose.
  • After you’ve put in new brake fluid it’s always a good idea to clean the brake caliper and main reservoir area to get rid of any brake fluid that spilled out.
  • Put some lube on the main reservoir screws to make them easier to take off next time.

Let me know your thoughts and any questions you have. Like this article? Feel free to give it a share!

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Jon Webber

I'm by no means an outdoors or fishing expert, but it's something I've been interested in for over 20 years. This site is where I test out different gear and techniques to see what actually works.

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