New Uni air filter kit for Honda CB500 4 cylinder and CB550 models listed below. They will fit carburetors with an inlet outer diameter (OD) of 1 1/4" to 1 1/2". These filters do require oil and are completely washable. They feature black caps, dark-gray / black water-retardant foam element. The overall length is 2 1/2". Jetting changes may be required. NOTE: EPA regulations may prohibit stock carb adjustments for post-1978 street motorcycles.