Big Bore 300cc Cylinder and Piston Kit for Montesa-HRC 4RT. High quality product. Greater capacity gives the engine added torque on the bottom and more power on higher revs. Smooth low RPM, and powerful high RPM. Engineering and production 100% made by S3. Heavy duty casting, with greater water capacity and more water circulation, flux spiral. The kits are delivered ready to fit on the engine, with cylinder and piston already assembled, and gaskets sets. Cylinder with NI-CA-SIL S3CYL®. More power, more dreams. For even greater performance, use the S3 titanium exhaust pipe (ref:EX-MON) and make injection settings.