Presenting master cylinder guard for RE Himalayan. Guard ensures you don't have to worry about debris damaging your motorcycle while riding. Why do you need a master cylinder on your motorcycle? The master cylinders on both the front and the rear of the bike are basically the same – a piston that pushes brake fluid down the lines, in turn forcing the pistons out to press the brake pads against the disc. What is the importance of protecting the cylinders? A master cylinder guard can protect it from the sudden impact of road debris.