Plexus - What is It? - iRV2 Forums Plexus is a cleaner for plexiglass or lexan windshield such as those on motorcycles The ammonia in regular glass cleaner will yellow lexan plexiglass Plexus comes in three formulas one of which is made to buff out scratches in plastic It can be found at any Harley dealer and most motorcycle dealer that cater to the road crowd