The K&N SU-1806 is a pair of reusable, high-flow replacement filter elements for the dual airbox on the Suzuki M109R Boulevard. Pleated media provides a large filtration area offering long service intervals, and the manufacturer describes multiple woven cotton gauze layers for filtration. Because the elements wash and re-oil instead of being replaced, the cost is spread across many service intervals.
A higher price than a disposable filter only pays off if the element lasts, and the manufacturer says the washable design offers a longer service life, helping reduce replacement costs while supporting extended maintenance intervals. The manufacturer also claims the media is designed to raise horsepower and acceleration, but no dyno figure was confirmed, so expect a throttle-response gain rather than a specific number. Owners on user forums say the K&N cost less than the dealer's stock filter. Warranty terms are listed differently across the manufacturer's pages, so confirm current coverage before buying.
Fitment is where buyers should slow down. The manufacturer's page lists the M109R Boulevard across 2006-2024, while other fitment tables show narrower ranges, so verify your model year and submodel, including the Boss and Limited variants, before ordering. Searches for "SU-1806 M109R dual airbox install" and "washable Boulevard M109R air filter" return the same core fitment question. Owners on user forums advise seating the filter fully, tightening cover screws evenly, and oiling the elements if they arrive dry.
The manufacturer's product page lists the Suzuki Boulevard M109R from 2006 through 2024. Other fitment tables show narrower ranges, so confirm your model year and submodel with the manufacturer before ordering.
The manufacturer describes the elements as pre-oiled and ready to ride. Owners on user forums have reported receiving unoiled filters and recommend applying K&N's cleaner and oil kit before installation.
The manufacturer's guidance describes removing the stock elements from the existing filter assembly and replacing them with the K&N units. Owners on user forums report the cover can be fiddly to reseat, so check the seal and screws after installation.
The manufacturer rates this job as easy to moderate, typically needing only a screwdriver and about 5 to 10 minutes. Remove the stock elements, check that the new filters seat fully, and confirm the included compression limiters are in place for a proper seal. Owners on user forums advise tightening cover screws evenly so the plate does not twist, and recommend oiling the elements before installation. Take care with the screws, since one owner reported stripping one.
