Brake Master Cylinder front w/ lever GY6 125/150cc

Brake pump

The brake pump or brake master cylinder is directly connected to the brake, i.e. this is where the pressure is transmitted to the brake caliper when you press the brake lever or brake pedal.

If the brake pump is defective, this is not necessarily noticeable by leaking brake fluid, but by the fact that the brake becomes spongy and soft, which significantly reduces the braking performance.

How to Overhaul a brake pump

For inexpensive brake cylinder repairs, we carry repair kits that include gaskets and all the necessary materials for overhauling and repairing the master cylinder.
You will need to completely disassemble the brake cylinder, disconnect it from the brake hose and remove all clips, snap rings and bolts to remove the seals.

If you can't find a repair kit that fits your model, or if overhauling is too much work for you, you can also buy a complete brake master cylidner in OEM quality, a universal brake pump, or even a racing brake cylinder.

Changing the brake pump

To remove the brake pump, simply disconnect it from the brake line by removing the banjo bolt.
Do not lose the copper washers (and while you're at it check them and replace them if necessary) in order to reattach them later on both sides of the banjo bolt.
Then open the reservoir, fill it with brake fluid and bleed the system.