Upgrading the air filter in the 1989 Yamaha Moto 4 YFM350ERW to a K&N air filter. A custom housing had to be made for the air box in order to accept the new filter. This design is a significant upgrade from the factory filter.
Upgrading the air filter in the 1989 Yamaha Moto 4 YFM350ERW to a K&N air filter. A custom housing had to be made for the air box in order to accept the new filter. This design is a significant upgrade from the factory filter.