"We have sold 7 of these in the last 6 months"

Just like human beings, motorcycle engines need clean air to run efficiently. The air filter, therefore, plays a vital role by filtering out the dust, dirt, and debris as the air is sucked into the engine. Without it, the contaminants would cause incomplete combustion, increased fuel consumption, and a smoky exhaust system.
The pollutants would wear down key components like the engine pistons and the walls of the cylinders, leading to expensive motor repairs.