Improved Capped Magneto Flywheel Rotor for Kawasaki

Ninja 400, Ninja 500, EX400, EX500 and Vulcan 454, 500, LTD, EN400, EN500 - 1985-1996

This is RMSTATOR's improved capped magneto flywheel rotor, a heavy duty replacement designed to cure a well known weakness in the original Kawasaki flywheel. RMSTATOR explains the problem directly: low quality epoxy was used on OEM flywheels to secure the magnets to the rotor body, and over time and many heat cycles that epoxy fails, allowing the magnets to come loose and contact the stator, potentially causing catastrophic damage. Part number RMS120-104078 replaces Kawasaki OEM 21050-1171 and 21050-1110, and covers the Ninja 400 and 500, EX400 and EX500, and Vulcan 454, 500, LTD, EN400 and EN500 from 1985 to 1996.

The RMSTATOR solution addresses the failure on three fronts. An improved high temperature epoxy, stronger than OEM specification, holds the magnets to the rotor body. A high grade steel cap is fitted over the magnets to stop engine oil from degrading the epoxy bond, which is what allows the original units to let go. Each rotor is then precisely balanced to eliminate crankshaft vibrations, and RMSTATOR backs the part with a two year warranty and tests every unit before it ships. The rotor measures 129 mm across the exterior diameter and 106 mm across the interior diameter, with a 25 mm exterior and 16 mm interior centre housing diameter, and a thickness of 42 mm on the exterior and 33 mm on the interior. One point to note before starting the engine: RMSTATOR advises that adjusting the air gap is necessary, by rotating the flywheel so the raised node lines up with the pick-up or pulser coil, then setting the gap as close as possible but no less than 0.010 inches.