K&N Air Filter Socks | BMW R nineT

An air filter sock protects the air filter from weather and coarse particles while letting air flow toward the engine. It is a textile cover that extends the filter's life without compromising its performance.High-performance air filters, in oiled cotton or foam, are effective on the intake side but vulnerable on the outside: rain can soak the oil, dust builds up on the surface, and road spray quickly clogs the first layers. The sock acts as a pre-filter: it blocks liquid water and coarse particles before they reach the filter, while staying breathable enough not to restrict the intake. Without it, a high-performance filter clogs much faster, particularly on a motorcycle with exposed air filters.The K&N socks we offer in our catalogue play exactly this role on the K&N air filters of your BMW R nineT.

An air filter sock designed for a high-performance filter does not significantly reduce engine performance, provided you use a breathable model adapted to the filter. The choice of product is the key.A sock that is too dense or unsuitable can indeed restrict the intake and drop the gain. By contrast, a sock designed by the filter manufacturer allows enough airflow to preserve the performance brought by the high-performance filter. The high-density breathable material blocks water and coarse particles without restricting airflow, which keeps intake airflow close to that of a bare filter under normal road conditions.As these socks are produced by K&N themselves, their compatibility with K&N filters is guaranteed without compromising performance.

These K&N socks are compatible with the K&N air filters on the BMW R nineT, provided they are indeed K&N filters and not another brand. The sock is sized to fit the matching K&N filter.If you have fitted the K&N air filters we offer in our catalogue on your R nineT, these socks fit directly with no adaptation. If you use air filters from another brand or a different format, check before ordering that the size matches your filter. K&N offers these socks in several sizes depending on diameter.For any verification, our FCR Accessoires team is available on +33 5 49 62 03 26.

K&N socks are fitted in a few seconds, with no tools and no removal of the filter.The procedure is as follows: 1. Identify the air filter to protect on your BMW R nineT. 2. Slip the sock over the filter, starting from the top and unrolling progressively toward the base. 3. Position the elastic edge against the base of the filter, so it sits around the perimeter. 4. Check the sock is properly centred and that no fold is blocking the intake. 5. Repeat the operation for the second filter. The fitting is reversible at any time: the sock removes just as easily for cleaning, inspection or filter replacement.

Care for K&N socks is done with plain water, without aggressive detergent, and they are reusable season after season.The frequency of care depends on use conditions. In urban or highway riding, cleaning every 2 000 to 3 000 km is enough. In dirtier conditions (off-road, dusty area crossings, prolonged rain), more frequent visual checks are recommended. To clean, remove the sock from the filter, rinse it in plain water to flush out dust and debris, let it dry fully in open air, then refit it. Avoid solvents and high-pressure cleaners, which can damage the textile weave.This simple care allows the socks to last several seasons without loss of efficiency.

K&N socks are sold separately from K&N air filters. They are two complementary products designed to work together. The K&N air filter brings the intake performance gain, it is the active component of the system. The sock is a protection accessory that extends the filter's life in the conditions where it is most exposed. On a motorcycle like the BMW R nineT fitted with exposed air filters, both are meant to be used together: without a sock, the K&N filter clogs faster and its maintenance needs to be more frequent. It is this coherent pairing that led us to include both products in our R nineT catalogue.