by Chris Gilliland
Honda's 1993 TRX300 FourTrax all-terrain vehicle was equipped with a hydraulic front brake system. Unlike standard hydraulic brakes, which are typically paired with disc-like brake rotors, the TRX300 relied on a drum-style brake assembly attached to both front wheels. Over time, the fluid within the brake system could develop air bubbles and absorb water in the form of condensation, reducing the brakes' efficiency. This is often felt as reduced braking capability and a soft, almost sponge-like feeling from the brake lever. Removing water and air-contaminated brake fluid is done through a set of valves built into the front brake.
Loosen the front wheel lug nuts on both sides of the ATV, using a 17 mm socket and a breaker bar. Lift the front wheels off of the ground using a jack placed beneath the ATV's engine. Unscrew the lug nuts and pull both wheels off of the front wheel hubs.
Remove the front brake master cylinder's rectangular fluid reservoir cover using a Phillips screwdriver. Pull the inner diaphragm out of the reservoir, then suck out the old brake fluid using a syringe or hand pump. Refill the reservoir with fresh DOT 3 brake fluid until the fluid is level with the top of the round reservoir sight gauge.
Tap the front brake master cylinder and the upper brake line fitting lightly to dislodge any trapped air bubbles, then pull and release the brake lever several times to draw fresh brake fluid into the brake circuit. Refill the reservoir if the fluid level drops significantly.
Remove the rubber dust cap from the left front brake bleed valve, located at the rear of the left front wheel hub. Push a three-foot length of clean 1/4-inch inner diameter plastic hose over the bleed valve, then lay the free end of the hose in a plastic catch container.
Have an assistant pull in and hold the front brake lever firmly in place.
Turn the bleed valve counterclockwise a quarter-turn using an 8 mm crescent wrench. A small stream of brake fluid will shoot into the plastic hose as the valve is opened. Turn the valve counterclockwise to close it, then instruct your assistant to slowly release the brake lever. Repeat two to three times to fill the plastic hose with brake fluid.
Inspect the condition and color of the brake fluid trapped within the hose. When fresh, brake fluid is clear and has a light tan hue. If the brake fluid appears dirty or contains air bubbles, you must continue bleeding the brake circuit.
Open the bleed valve and have your assistant pull in and hold the brake lever in place. Close the bleed valve, then have your assistant slowly release the lever. Continue to bleed the left front brake in this manner until the fluid caught in the hose is free of air bubbles and clear.
Pull the hose off of the left front brake bleed valve using a shop towel.
Wipe away any spilled fluid, then push the rubber dust cap onto the valve. Refill the master cylinder reservoir with DOT 3 brake fluid.
Remove the rubber dust cap from right front brake bleed valve, then push the plastic hose onto the valve. Bleed the right front brake, using the same method as the left brake. Stop when the brake fluid is clear and free of air bubbles.
Pump the front brake lever in several times. The lever should feel firm a quarter to half of the way into its stroke, indicating that there is hydraulic pressure in the brake circuit. If the lever feels soft and provides a sponge-like sensation, re-bleed the front brakes, starting with the left brake.
Pull the hose off of the left front brake bleed valve, using a shop towel. Wipe away any spilled fluid, then push the rubber dust cap onto the valve.
Refill the master cylinder reservoir with DOT 3 brake fluid until the fluid level is at the halfway point in the reservoir's sight gauge.
Reinstall the reservoir lid and inner diaphragm.
Mount the front wheels onto the wheel hubs, then screw the lug nuts into place by hand. Lower the wheels to the ground and remove the jack. Tighten the lug nuts to 47 foot-pounds using a torque wrench.
References
Tips
Over-filling the reservoir can cause the fluid to leak or build up enough pressure to lock the brakes. Things You'll Need
Warnings
Writer Bio
An avid motorcyclist, Chris Gilliland has immersed himself into the two-wheeled world while balancing work life and raising three daughters. When he is not managing the parts department of a local, multi-line motorcycle dealership, Gilliland can often be found riding, writing or working on his motorcycle blog, Wingman's Garage.
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As an ATV owner, it’s a good idea to learn a few basic mechanical skills, such as being able to bleed the brakes when needed.
This job is relatively easy to do and can save you quite a few bucks on mechanical expenses. Follow this guide, and you have a great chance at succeeding with just about every brake bleeding job.
Hydraulic brake systems use special brake fluid to transfer the energy from your hand or foot and down to the brake caliper. The fluid is essential for proper brake function.
Inside the caliper, a piston is being activated by the brake fluid when pressure is being applied. The piston will then press the brake pad against the brake disc, creating friction to stop the bike.
Bleeding the brakes means letting out some of the brake fluid to remove trapped air or to replace the brake fluid altogether.
There are two leading causes for having to bleed the brakes on your ATV:
Brake fluid cannot be compressed, but air can. If even the smallest bubble of air enters the system, the brakes will not function as they should but rather feel soft and squishy. To get all of the air out of the system, we need to “bleed” the brakes.
Air may enter the system if you replace or disassemble one or more components connected with the brake line, such as removing the brake caliper for a service. Or you may have a brake line come loose, allowing air to enter the system.
Please note that air should not get into the system under the regular operation of the ATV. Therefore you have to locate and address the cause of the leak before bleeding the brakes.
Another common situation where knowing how to bleed the brakes comes in handy is when it is time to replace the old brake fluid with new.
So-called flushing the brakes.
Brake fluid is hygroscopic, which means it absorbs water over time. Also, it breaks down when being exposed to heat. The fluid closest to the brake calipers is the most affected because of the heat produced when breaking.
Healthy brake fluid should look clear or with just a slight amber color. If it looks like cola, it is well overdue for being replaced.
Bad brake fluid will negatively affect your brakes’ performance, so make sure you replace it in time. Luckily this job is both cheap and usually relatively easy to do.
It’s a good idea to completely replace the brake fluid on your bike every time you change your brake pads or at intervals according to your ATV service manual.
Most ATV’s have one master cylinder for the front brakes on the handlebars and another one for the rear brakes in a separate location. The reservoir for the foot pedal is often located a bit away from the actual cylinder unit.
The setup will vary from model to model. Some bar-mounted master cylinders will operate both the front and rear brakes as well.
The method for bleeding them, however, is pretty much identical.
To locate the master cylinder(s) on your bike, trace the brake lines from the brake caliper. You need to address each brake fluid reservoir connected with the brake you are having problems with.
Here you can see the hose running from the rear brake master cylinder and up to the brake fluid reservoir.If you are not sure where your problem is, you might as well bleed the brakes on all four wheels. Then start with the caliper the furthest from the master cylinder and move against it.
Let us begin with the standard method for bleeding any hydraulic brake system. It requires almost no tools or previous mechanical experience.
Just follow the steps below:
Optional (but recommended):
Use it to collect old brake fluid for proper disposal. Not only will the environment thank you, but you will keep your shop and ATV clean as well.1. Jack up the ATV.
Start by jacking up the ATV and remove the wheels where you are bleeding the brakes. It is possible to bleed the brakes without removing the wheels, but you will get much better access to the bleed nipple with the wheel out of the way. If this is your first time bleeding the brakes, I always recommend removing the wheels.
2. Remove the brake fluid reservoir cap.
You will need to add new brake fluid as the old goes out. The lid on the reservoir up on the handlebar is held in place with two hex screws. Be careful as the threads strip quite easily.
You find the brake fluid reservoir up on the handlebar.Depending on the bike’s age and the time since the screws were removed, they may be grown in there pretty good.
This is where the small impact drivers come in handy. Find the correct bit and use the driver by giving a light tap.
This will knock loose any corrosion and open the screw slightly at the same time. One knock is usually sufficient. The reservoir for the foot pedal usually has a twist cap that unscrews by hand.
3. Clean the cap and rubber diaphragm thoroughly.
You do not want to contaminate the system with debris, dirt, or water when reassembling it later.
Clean the area surrounding the brake fluid reservoir before opening the lid carefully.4. Top of the brake fluid up to the maximum level mark.
Pay close attention so that the brake fluid level in the brake fluid reservoir never drops below minimum while bleeding the brakes. You may need to top off the reservoir several times before you are finished.
It’s recommended that you reinstall the lid before moving to step 5. While it is possible to pump the brakes with the cover off, you run a significant risk of quirting brake fluid all over your bike if you pump the brakes too hard or too fast.
5. Pump the brake lever or foot pedal 3-4 times, depending on which brake system you are bleeding.
Remember to pump carefully if you do this with the lid open! Then keep the lever-activated by hand or by putting on a spring-loaded clamp to keep it under tension.
A spring-loaded clamp or even a bungee cord may be of good help if there is no one around to assist you.6. Open the bleeder valve.
Start with the valve that is the furthest from the brake fluid reservoir. It is located on top of each brake caliper and is opened by turning it anti-clockwise about half a turn. You should see brake fluid squirt out of the bleeder.
Let the brake fluid flow into a container to keep your ATV and garage clean.7. Close the bleeder valve when the brake lever or foot pedal reaches about 80% of its overall travel length.
Do NOT overtighten the bleeder. The threads in the aluminum brake calipers strip easily!
8.
Repeat until the brake fluid that comes out of the bleeder is completely free of air bubbles.
This may take a while, depending on how much air there is in the brake lines.
9. Follow the same procedure on all four wheels.
Some bikes have just one combined brake caliper for the rear wheels.
10. Top off the brake fluid reservoir up to the maximum mark.
The mark may be a line found inside the reservoir or an inspection gauge on the side. Other reservoirs have a gauge on top of the reservoir cover that is white when brake fluid levels are low but turns black when the correct level is reached.
This is how it should look like when you have enough brake fluid in the reservoir.11. Replace the lid and rubber diaphragm.
Make sure it is seated properly. Do not over-tighten the bolts. You are now done and can reinstall the wheels.
The manual method works fine most times, but not always.
It comes with a few annoying downsides as-well:
The master cylinder on an ATV and the piston inside it are relatively small compared to those you find on cars on any other larger vehicles. Because of its small size, it can only pump a relatively small amount of brake fluid with each pump.
This makes the standard method of bleeding brakes work less efficiently on smaller brake-systems found on ATVs, UTVs, dirt bikes, motorcycles, or snowmobiles.
The amount of fluid being pumped may not be enough to move the bubbles of air out before you bottom out and have to start a new pumping cycle.
It will take about 10-15 minutes to completely flush the brake system on an ATV using the standard method. It will take even longer if you do it on your own.
If you’re having problems removing all of the air, you may be looking at several hours of struggle before you eventually succeed or give up.
When you pump the brakes, you force the air downwards against the bleeding valve.
Air is lighter than brake fluid and will always want to go upstream, away from the bleed valve.
Combined with a small pump, you may not be able to get all of the air down to the bleed valve.
So then what? Luckily there is another cheap and easy method for bleeding the brakes that work very well.
Vacuum bleeding is another cheap and easy way you can use to bleed the brakes properly.
In addition to the five first bullet points listed for the standard method, you will also need a hydraulic brake bleeder tool.
These come in various shapes, but they all work by the same principle: they suck the brake fluid down and out through the bleed valve using a vacuum.
Some models use a hand pump to create the vacuum. They will also have a one-way check valve that allows brake fluid to flow out of the brake caliper without letting air back into the system when you release the pump.
Other models connect to an air compressor to create the suction effect.
Now you should be ready to tackle almost any brake bleeding jobs. But from time to time, even the vacuum pump won’t be sufficient to bleed all of the air out of the system.
Before taking the bike to your dealer, it’s worth reading through this post on what to do when you’re not having success bleeding the brakes using the methods described above.
Alternatively, you can try to reverse bleeding the brakes on your ATV.
ATV brakes are a basic safety system and should work perfectly. And if you notice the slightest slippage or decrease in the efficiency of the nodes, the system needs to be checked. Therefore, let's figure out how to pump the brakes on an ATV and diagnose all the components.
The first fluid change is recommended as soon as the rider has purchased the ATV.
The fact is that many manufacturers fill in the cheapest composition, which does not have a high operational resource.
After buying a used ATV, you also need to service the brake system: change the fluid, check the hoses and pads. Remember that during the operation of equipment, moisture and air enter the composition. This leads to the formation of corrosion and even freezing of the liquid in winter. For example, if the composition contains only 3% water, its operating temperature drops from 230 to 165 degrees.
You need to figure out how to pump the front and rear brakes of an ATV even in case of their “failures”. If the lever has lost its elasticity, then air or moisture has accumulated in the system, which has affected the characteristics of the fluid.
Before you adjust the brakes on your ATV, have the necessary tools ready. To bleed the system you will need:
It is best to take a bottle and a tube from a dropper, which can be connected to a drain fitting. Thus, the spent composition will not get on the parts of the ATV. It is worth noting that in order to pump the ATV, you need a partner who will clamp the brake lever. If there is no assistant, you can fix the position of the brake lever with a belt.
Bleeding the brakes scares many motorists. However, the procedure itself is very simple, so even a novice ATV rider can handle it. The rider only needs:
Before you bleed the front brakes on your ATV, make sure you have access to the caliper. If you can’t get to the node, you need to remove the wheels. 
Such pumping is performed until the lever becomes elastic. This procedure is carried out for all calipers (front and rear). But if the brakes on the ATV do not pump, then you need to find places in the system where air accumulates and eliminate them.
Experienced motorists recommend using only high-quality brakes that are suitable for specific temperatures. This means that for summer and winter you need to choose different compositions.
Riders also advise:
Also buy a spare brake. If the documentation indicates that 0.5 liters of fluid is needed to bleed the system, buy 1 liter of the composition. The fact is that the recommended volume is indicated based on the experience of specialists. A novice ATV rider can spend more brakes.
19.02.2021 4455
As with any vehicle, the brakes on an ATV must work properly, as the safety of the driver depends on it. Chinese spare parts, from which almost every ATV is assembled, are not of high quality. Some ATV models require service immediately after purchase. Therefore, the question of how to pump the brakes on an ATV is very relevant.
Contents
Bleeding the brakes on the ATV is required if it becomes noticeable that the efficiency of the discs has begun to decrease significantly.
In this case, it is necessary to immediately check the integrity of all elements of the system, check the condition of the pads, discs, hoses, etc. If all components are in good condition, in this case it will be necessary to bleed the brakes of the ATV.
This procedure is quite simple, even an inexperienced driver who has recently purchased an ATV can handle it. However, in the process of work, you will need to show care, patience and some professionalism. It is recommended to bleed the brakes with a partner.
This work must be treated responsibly. The safety of the driver of the ATV, as well as his passengers (if any) depends on the correctness and sequence of all actions.
If you are interested in how to bleed the brakes on the ZF Moto 500, Stels leopard 500, Stealth 500 GT or other models, it is enough to consider the general principles of modification. The process is identical for most ATV models. Bleeding the front and rear brakes is not much different.
Note that the brake circuits on ATVs are separate. The system has two brake reservoirs that are not connected to each other. They are responsible for stopping the rear or front wheels, respectively. On some models, the brake reservoir is responsible for all four wheels of the ATV.
If there are two tanks, the first one is on the steering wheel. He is responsible for the front wheels. The second brake reservoir is located on the frame. He, accordingly, stops the rear wheels.
To bleed the brake system, you will need to prepare the necessary tools. Required for work:
DOT4 and DOT fluids are universal.
To bleed the brakes, you must first unscrew the cap that closes the brake reservoir. Next, you need to evaluate how much brake fluid is inside. Most often, it needs to be topped up. Pour brake fluid into the reservoir up to its very edges.
There must be no air bubbles inside the system. Therefore, periodically you need to control the liquid in the tank. If necessary, the composition is added.
Fit the prepared drain tube onto the fitting. The second end is lowered into a previously prepared container. Next, you need to ask your partner to squeeze the brake handle. It is not recommended to release it until the work is completed. Some models of ATVs will require you to depress the pedal. The fitting must be unscrewed 1/8 turn (sometimes more, depending on the model), and the key must be prepared in advance by 8.
Next, the brake lever is pressed, and at this moment the fitting is twisted.
The handle is released, and then the procedure is carried out again. In this case, the amount of liquid inside the tank is constantly monitored. If necessary, a new composition is added to the system.
After some time, the partner will say that the handle (or pedal) has completely failed in its seat. However, at this moment, you can not let her go. After the information received from the partner, you will need to tighten the drain fitting.
The procedure is performed several times. This must be done until clean (new) brake fluid is poured into the prepared container. It should not contain air bubbles. If they are, the new composition was not filled to the very top of the tank. This must be taken into account when changing the brake fluid in the system.
If the brake fluid needs to be replaced, it will be enough to purchase 0.5 liters of the product, which is enough for both circuits. However, it is worth noting that such an amount of brake fluid allows you to replace the composition with “jewelry” accuracy.
More often than not, the volume of the product is not enough, so it is better to purchase brake fluid with a margin. 1 liter is enough. If air bubbles need to be removed from the brake system, a liter is the minimum amount. Sometimes, to carry out such work, you need even more funds. Two liters of liquid may not be enough to find and drive out all the bubbles.
When the brake fluid is drained from the system, it will be necessary to bleed each of the existing calipers. When this procedure is completed, you need to put the tank cover in its original place. Before that, you need to assess the condition of the rubber gasket. If it is worn, the seal will need to be replaced.
There must be no brake fluid left in the system at all. After the procedure, you will need to pour a new agent into the tank. This will take several hours. The liquid is poured into the tank, and then wait until it reaches the caliper. At this time, the fitting must be open.
