I find that one of the most neglected maintenance items on a motorcycle is the brake fluid. The worst part about it is the fluid change procedure only takes ten minutes – it’s faster than an oil change! Most motorcycles state to do it every two or three years. The reason for the frequency is due to the limited amount of fluid in a motorcycle and the critical nature of the brakes on a motorcycle.
Brake fluid absorbs moisture rapidly. Moisture comes from multiple sources in a brake system, even if it is closed. Condensation from environmental factors. It could be a cold garage and you pull it out on a hot day. Winter time causes condensation on motor oil and brake fluid. The super low temperatures at night then warmer temperatures during the day. Or if you ride in the cold and heat up the brake fluid by using your brakes a lot. Condensation gets in from other ways too, but the bottom line is it does get in there.
Why is this a big problem? Compression. Water is far more compressible than brake fluid. So as moisture builds up, your brakes become squishy and do not have the stopping power that they should.
Another problem with water in the brake fluid – corrosion. Parts start deteriorating and even rusting. Holes start forming in the brake lines from the inside out.
Air can also work its way into the system over time. This doesn’t happen much if the system is well maintained and there are no leaks, but it can occur. A lot of people just bleed their brakes (remove air) on occasion and not do a full change. You’re already half way there with bleeding, do the full change!
“But the bottle says good for 50,000 miles!”
Yea, sure – but it doesn’t have how long it is good for time wise. That bottle is also going with the larger market, passenger vehicles (cars, trucks, suvs, vans).
Follow the factory recommendation for your motorcycle, but most common is two or three years to do a full change. I personally do it every year since it is such an easy process.
Motorcycles with ABS may not get a full change unless you have the systems to actuate the ABS modules. That’s okay though, as the other 95% gets changed and then if you trigger the ABS the fluid will work its way through. My Kawasaki motorcycle is supposedly an open system when off, making it a full 100% change.
So get out there and change your brake fluid before the riding season comes up. Brake fluid is cheap, just make sure you get the right stuff. DOT 4 is reverse compatible with DOT 3. Do not put DOT 3 in a DOT 4 motorcycle though. Make sure your motorcycle isn’t DOT 5, in which case you will need DOT 5. Check your owners manual, or most times the fluid type is printed on the reservoir cap.
Below is a video I did for the brake fluid change on my 2021 Ninja 1000SX. The procedure will be very similar across all motorcycles.
The following products may be helfpul:
- Pneumatic brake bleeder – https://blueeyedrider.com/tools/four-uncles/pneumatic-brake-bleeder
- Manual brake bleeder – https://blueeyedrider.com/tools/mityvac/brake-bleeder
- Fluid syringe (to get fluid out of reservoir) – https://blueeyedrider.com/tools/generic/fluid-syringe
- DOT 4 Brake Fluid – https://blueeyedrider.com/supplies/prestone/dot-4-brake-fluid
- Brake Kleen – https://blueeyedrider.com/supplies/crc/brake-kleen
- Microfiber Towels – https://blueeyedrider.com/detailing/microfiber-towels
- Silicone grease – https://blueeyedrider.com/supplies/ags/sil-glyde-grease
