The Kawasaki Ninja 400 and Z400 have a problematic coolant seal between the cylinder and case on the front of the engine. This poorly designed OEM seal has a tendency to fold over or deform over time, causing a coolant leak on the front of the engine that is labor intensive to fix since the cylinder head must be removed. After replacing numerous OEM seals in race and street bikes, we have designed and manufactured our own Norton Racing seal to replace the OEM seal. Our Norton Racing Cylinder Coolant Seal features a machined aluminum body to fill the OEM seal location and dual o-rings captive on top and bottom to eliminate potential failures. Highly recommended as a preventative measure in all race bikes and recommended as a replacement for the OEM seal in any case (Track or Street bike) where the OEM seal has failed and must be replaced.