The K&N RU-4650 is a round-tapered, universal clamp-on air filter built on K&N's oiled cotton gauze media, which is reusable rather than disposable. It measures 5 in across the base and 6 in tall, with a 4 in top and a centered flange that has a 3 in inside diameter, so it suits intake tubes sized for a 3-inch clamp-on. K&N markets its universal line for racing vehicles, radio-controlled cars, generators, snowmobiles, tractors and other equipment. Because it is a universal design rather than a direct-fit part, the flange must match your intake and seal properly.
The case for paying more than a basic disposable clamp-on comes down to reuse and long-term value. The cotton gauze is washable, so you clean and re-oil it instead of replacing it, and K&N backs the element with a 1-year limited warranty. The manufacturer's cleaning rules are strict: use only K&N filter cleaner and avoid gasoline, steam, caustic or strong detergents, parts solvents, and high-pressure washing, which can damage the gauze and harden the rubber end cap. Re-oil with about 0.95 oz (28 ml) of K&N filter oil. Shoppers looking for a 3 inch flange cotton gauze clamp-on, a washable red universal intake filter, or a 5 inch base tapered air filter will find the key specs below.
No. The manufacturer sells this as a universal clamp-on filter for a wide range of applications rather than a filter built for one make or model. Confirm that your intake tube accepts a 3 in inside-diameter flange before ordering.
The manufacturer lists a re-oiling amount of 0.95 oz (28 ml). Apply the oil evenly across the gauze once the filter is fully dry.
Yes. The manufacturer describes the filter as washable and reusable. Its cleaning instructions call for K&N filter cleaner only, followed by air drying and re-oiling.
Because this is a universal clamp-on filter, there is no vehicle-specific bolt-in procedure. The main job is making sure the 3 in flange fits your intake tube and that the flange seats and clamps without leaks. Once installed, confirm there are no whistling or hissing sounds from the intake, which would indicate an air leak. For cleaning, follow the manufacturer's sequence: tap out loose debris, soak the media with K&N cleaner, rinse gently from the clean side, let it air dry completely, then apply K&N filter oil evenly before reinstalling. Do not reinstall a filter that is still wet or over-oiled, since excess oil can contaminate intake sensors.
