Brake fluid is one of the fluids in your motorcycle, and manufacturers recommend the replacement of the fluid every two years.
Considering the importance of proper brake performance to motorcycle riding, you need to test it at least every year. Fortunately, there are three simple ways to do that. They include sight, feeling or using a tester.
Most motorcycles use hygroscopic brake fluid. That means the brake fluid in the bike will absorb water from the atmosphere. Even two percent of water in the braking system can have a serious impact on the braking performance.
Is old brake fluid an issue?
Hygroscopic fluids absorb water with time. Pure brake fluid does well as the brakes heat. However, brake fluid containing water does poorly as the brakes heat.
Another issue with moisture in your brake fluid is that it can cause corrosion internally, leading to failures in the system.
How to tell if motorcycle brake fluid is bad
Brakes are key to motorcycle riding; thus, they should always be in good form. The three ways to test the motorcycle brake fluid are by feel, sight and use of a tester device.
Testing by sight
One indication that brake fluid has absorbed moisture is a whiskey-like (or darker) appearance. That is why your motorcycle brake fluid reservoir is most likely either semi-clear or clear, so you can see the color of your brake fluid.
Another method of telling whether your motorcycle brake fluid is good or bad is by imagining giving a urine sample to a medic. Does the hue look healthy, or does it look like you need some fluids?
Testing by feel
Another indication that your motorcycle brake fluid has absorbed a significant amount of moisture is a squishy or spongy feel to the brake pedal. When you press the pedal, it should be crisp and firm, not squishy.
Using a brake fluid tester
An electronic brake fluid tester reads the amount of moisture in the fluid, letting you know whether or not you should replace it. If you are new to motorcycle maintenance, and you are not confident in your experience, consider buying a tester to assist you. To use the tester, remove the lid of the brake fluid reservoir and the diaphragm and put the tester in the brake fluid. The lights on the side will indicate whether the brake fluid is BAD (over 3% moisture), OK (1% to 2%) moisture or GOOD (0% moisture).
Take care not to spill DOT-4 brake fluid on the motorcycle when using the tester as this fluid is corrosive and might damage the motorcycle paint.
A brake fluid tester is a wonderful tool for a first-timer who wants peace of mind. Nevertheless, it is not compulsory. You can save money by using the pee test (sight test) or the butt test (feel test).
How to change your motorcycle brake fluid?
You can change the brake fluid by yourself following these steps:
- Remove the lids, covers and diaphragms to reach the master cylinder reservoirs.
- Draw out old fluid with a syringe, siphon or turkey baster.
- Replace the brake fluid in the reservoir with new fluid.
- Bleed the brakes.
- Redo the process on the other brake.