Suzuki has issued a recall for the Hayabusa. A fault in the brake pump can cause underpressure in the front brake line, which pulls the pistons in the caliper and creates a large clearance between the brake piston and the brake pad.
Due to mispositioning of the primary cylinder port in the front brake master cylinder on the two-year completely restyled GSX-R1300 Hayabusa, it can become blocked when the primary o-ring swells. When the brake then cools down again, underpressure is created in the line.
As a result of the vacuum, the pistons in the caliper are pulled inward and thus detach from the brake pads, creating excessive play between the brake pad and the disc brake rotor. The next time the brake is applied, the brake lever has a much longer free play before the brake pads engage.
In September 2021, Suzuki received a first report from the Portuguese importer, regarding a Hayabusa whose front brake was not working. However, inspection revealed that there was no front brake failure, but that the brake lever stroke length could be increased. However, after the front brake was squeezed a few times, the problem was solved.
Because the problem had been solved, no further investigation could be done and the cause could not be found, so the brake pump was sent to Japan for further investigation.
That examination revealed that the primary o-ring had swollen and had become flat on the outside. Further testing revealed that when the brake was released, the primary cylinder port could be blocked by that flat o-ring. If the temperature of the brake fluid then dropped, a negative pressure was created in the brake line.
At the Suzuki dealer, the brake pump will be replaced with a new one whose positioning of the primary port has been adjusted to prevent the port from being blocked by the o-ring should it expand again.
– Thanks for information from Motorfreaks.