K&N Air Filter Replacement
The stock Suzuki air filter is about a $9 (cheap!) replacement unit, but the K&N filter is less restrictive
(K&N RD-0450, 1 7/8 I.D.).
Stock paper-element air filter (above with filter box cover removed) and replacement K&N oiled-gauze filter (below). K&N is slightly larger, but flange I.D. size is the same (1 7/8").
Original plan was to remove the entire air box and mount the K&N directly to the air flow meter. But the back of the box also supports the filter through two bolts on the box's top, so the back was retained.
K&N mounted to the plastic elbow that attaches to the air box and is secured to the air flow meter with 4 bolts. Rubber flange from the stock filter setup is discarded.
K&N Unit is larger that stock item. The K&N cost was $25, but is serviceable and should outlast it's paper predecessor.
K&N Unit is larger that stock item. The K&N cost was $25, but is serviceable and should outlast it's paper predecessor. Filter in place in the air box -- a tight fit. "Snorkle" was removed from the top of the box and discarded, along with the box cover.
Re-seal the air box mount to the airflow meter with thoroughly-chewed Bazooka bubble gum. If Bazooka is not available in your area, ThreeBond gasket sealer #1104 will do in a pinch.
Job complete. Intake roar -- if you can call it that -- is noticeably louder, but the XN85 is a pitifully quiet bike to begin with. Power feels about the same but once the turbocharger starts to build boost it maxes out more quickly. Boost is still tough to come by below 5,000 rpm unless under load.