The K&N SU-8009 is a direct-replacement high-flow air filter for the Suzuki VL800 Intruder (C800) and the C50/M50 Boulevard cruisers. It replaces the OE paper element (OE number 1378039G20) with a pre-oiled, pleated cotton gauze filter that the manufacturer says is designed to improve throttle response, horsepower and torque without fuel-management changes. It is washable and reusable and carries K&N's Million-Mile Limited Warranty, so you avoid repeat purchases of disposable paper elements at every service interval.
The filter uses an OE-style injection-molded frame that slides into the stock airbox with no cutting or fitting. Installation is a short job, but the manufacturer's install sheet requires moving the original cushions, steel washers and gasket onto the K&N element, and skipping that step can keep the filter from sealing. Fitment is the detail to verify first: the manufacturer's current product page lists the C50 Boulevard for 2009-2019 and the VL800 for 2009-2025, while its older flyer lists C50/M50 for 2009-2013. Confirm your model year before ordering, especially for the M50.
The manufacturer states that no fuel-management modifications are necessary to obtain the increased performance.
Yes. The manufacturer's install sheet directs you to move the four large cushions, four small cushions, four steel washers and the gasket from the OE filter onto the K&N element before installing it.
The manufacturer says the filter can run up to 50,000 miles before cleaning is needed, though the interval depends on riding conditions. Cleaning is done with K&N's recharger kit, part no. 99-5000.
The manufacturer rates this as an easy DIY job, typically 5 to 10 minutes with a screwdriver. Remove the stock filter, transfer the cushions, washers and gasket, clean any debris from the airbox, seat the K&N element, and reinstall the lid. The manufacturer warns that the procedure must be followed every time the filter is serviced, or the filter may not seal and engine damage could result.
