The K&N KT-7918 is a panel-style replacement element for the 2018 KTM 790 Duke, and the manufacturer describes it as washable and reusable for the 2018 KTM 790 Duke with a 799 engine. Its media is a stack of oiled cotton layers that the manufacturer says improves airflow and traps contaminants, and it is designed to install easily into your factory air box. Owners on user forums describe the stock element as paper, so the real comparison is a reusable cotton filter that gets cleaned and re-oiled instead of replaced.
Paying more than a basic paper swap is mainly justified by service life. The manufacturer rates the filter for cleaning every 50,000 miles under normal highway driving conditions and backs it with a No-Hassle Lifetime Limited Warranty. It is also listed as emissions legal in all 50 states. Be realistic about power, though: some owners on user forums doubt a measurable gain on the 790 and weigh recurring cleaning and oil costs against paper filters. Search terms this part matches: KTM 790 Duke K&N air filter KT-7918, reusable 799cc panel air filter, 790 Duke washable cotton air filter, 790 Duke airbox filter upgrade.
The manufacturer lists it for the 2018 KTM 790 Duke with the 799 engine. Published fitment years vary across sources, so confirm your bike's model year and engine with the manufacturer before ordering.
The manufacturer's guidance uses K&N's own cleaner, which is sprayed onto both sides of the filter and left to sit for 10 minutes. After rinsing and drying, oil is applied evenly along the crown of each pleat, allowed to wick for about 20 minutes, and touched up until the color is uniform.
The manufacturer states the filter is emissions legal in all 50 States and will not void vehicle warranty.
The manufacturer lists this as a quick DIY job of about 5 to 10 minutes, with a screwdriver as the only tool it calls for. Owners on user forums say the 790 filter is easy to reach, so the work is mainly opening the airbox, swapping the element, and reseating the cover. Oil the element before it goes in, and have K&N oil on hand, since enthusiasts on user forums note you need to buy it separately. Do not oversaturate: enthusiasts on user forums warn that excess oil can migrate onto the MAF sensor. Let a cleaned filter dry fully, and avoid compressed air to speed up drying.
