Internally, the 540-M4 is very similar to that of the 540-M3 that it replaces - it produces the same linear powerband and excellent mid-range feel that have become synonymous with Reedy's modified motors. However, changes can be good when they serve a purpose. In the case of the 540-M4, the inner bearing has been moved so that it is part of the can instead of the sensor assembly, which more precisely aligns the rotor within the magnetic field while reducing noise and vibration.
Externally, the motor has been shortened, which results in more centralized weight distribution within the chassis. The reduced length, combined with improvements to the can design, results in a 5-10g reduction in weight.
A balanced, high-strength rotor provides powerful fade-free performance. A variety of optional rotors are available to fine-tune for specific applications and tracks. Precision stainless steel ball bearings have been fitted to reliably accommodate high RPM loads.