The Destination of this research was to determine the effect of rotational speed on the characteristics of fatique in centrifugal casting alloy A 356 aluminium alloy two-wheeled vehicle with a low round and 350 RPM and 550 RPM middle round. The casting in this research using a centrifugal casting method. The materil used is a cast aluminium alloy A356. Variations rounds used in centrifugal casting is 350 and 550 RPM. Casting proses carried out by pre-heating the mold 250⁰C, 750⁰C, casting temperature and with the addition of titanium boron grain refiner 12,08%. Results foundry the made specimen for rotary bending fatique test in accordance with JIZ Z 2274 standar 1. The examination has been done is the rotary banding fatique test. The examination results showed that the wheels with a round 0 RPM produces a voltage amplitude relationship with the number of cycles σa = 350 RPM rotation have a relationship with the voltage amplitude and at 550 RPM rotation have a relationship with the voltage amplitude