All about the Kawasaki Ninja 250


Brake Fluid

DISCLAIMER: Brakes are vital for your safety. If you don't feel confident about doing the job correctly, take your bike to a professional. It's your responsibility to know what you are doing and to do it right. The information below is for your guidance only. YOU are the one ultimately responsible for making sure the job is done right.

For some reason many owners think that brake fluid lasts forever. They'll change the oil every 3000 miles, but never think to change the brake fluid. Why do you need to change brake fluid? Well, it made from chemicals that absorbs moisture and as its moisture content increases, its performance decreases. Brake fluid with water in it has a lower boiling point, which means earlier onset of brake fade. Moisture can also lead to corrosion.

I bought a 1990 Ninja 250 and one of my fist tasks was to take a look at the brake fluid. Of course the screws holding on the top of the brake fluid reservoir (on the right grip) were stripped from abuse by previous owners, so they had to be drilled out. Removing the top revealed a pretty clean looking brake fluid reservoir with some sort of unidentifiable brownish liquid in it. Time for a change.

Changing the brake fluid is pretty easy. Just be sure to keep everything clean. You do not want dirt in the brake system. This is my method:

  1. Get a NEW can of brake fluid. Stuff that been opened and sitting around for a few years may already have absorbed moisture from the air.
  2. Get the top off the brake fluid reservoir. If you are lucky the screws will come out. If you are unlucky you'll have to drill the heads off the screws with a ~1/4" drill, remove the top and then get the rest of the screws out with a pair of vice-grips.
  3. Suck out most of the fluid in the reservoir with a small plastic syringe (available from your local pharmacy), or maybe a turkey baster if it's all you have! If there is gunk in there, wipe it out.
  4. Fill the reservoir up with new, clean brake fluid of the right type (DOT4 for the Ninja 250, though you can use DOT3. DO NOT USE DOT5, it's not compatible).
  5. Take a short (~18") length of plastic hose (Home Depot) and place it tightly over the bleed nipple on the front brake caliper.
  6. Place the other end of the hose in a glass jar.
  7. Squeeze the brake lever and then, while keeping pressure on the lever, unscrew the brake nipple until you feel the brake lever slowly move all the way back to the grip. You should only need a fraction of a turn to open the brake nipple. You will see brake fluid start to flow down the hose.
  8. Then, when the flow has stopped and while still holding the brake level all the way back against the grip, tighten the bleed nipple. If you don't tighten the bleed nipple and you release the brake lever, you'll either suck old brake fluid or (worse) air back into the brake system. You do not want to do this.
  9. Slowly release the brake lever.
  10. Repeat steps 7-9 until you see clear, new brake fluid come out of the bleed nipple. WARNING. Keep an eye on the level in the brake reservoir. As it goes down, top up as necessary. You'll have to loop through this around 10 times. 20 wouldn't hurt.
  11. You're done.
  12. Make sure the brake bleed nipple is tight and remove the plastic tube. Don't get brake fluid on your hands or paintwork if possible. It's nasty stuff.
  13. Make sure the reservoir is filled to the proper level and replace the top (using new screws). Make sure everything is clean before putting the top back.
  14. Clean off the brake nipple. Squeeze the brake lever hard and make sure there is no leakage. Put a plastic/rubber cap on the bleed nipple to stop dirt getting into it.

On the 1990 bike the old brake fluid looked like coffee, complete with grounds. The new stuff is clear and pale yellow.

At this point repeat the whole process on the rear. This is easy because the reservoir has a plastic cap so drilling out screws will not be required!

Total time (if you don't have to drill out the screw heads), around 20 minutes. Total Cost, under $5

Bleeding the brakes

If the brakes feel "spongy" and get better if you "pump" them, you have air in the system. Getting it out is pretty much like changing the brake fluid. What should happen in that case is air should come out of the system along with the brake fluid. If you have an air bubble that doesn't want to come out, you can try injecting brake fluid INTO the bleed nipple (plastic syringe and plastic tubing). Just make sure not to inject any air! This will force the fluid up through the system and hopefully any trapped air bubbles(which want to move upwards anyway) will come out in the fluid reservoir. If you do this you will need to suck some fluid out of the reservoir as you force brake fluid into the system or it will overflow and damage your paintwork/plastic.