Few jobs on a K3 are as quick and rewarding as an air filter swap. It takes about half an hour, needs hardly any tools, and the bike breathes easier afterwards. Mine was overdue, so here is how it went.
I went from a K&N to another K&N. The old one had done its time and looked it: dark, clogged and properly gross. The replacement is lightly used and in great condition, so rather than buying new I gave it a fresh start with K&N filter oil before fitting.
Access is straightforward. Take off the seat, then lift or remove the tank to reach the airbox, and make sure the fuel lines and connections are supported rather than strained. Once the airbox lid is open, the filter lifts out. While it is open, wipe out any dust or debris inside the box so none of it gets pulled into the intake.
I used the K&N spray oil. Spray it evenly along the pleats in a light pass and let it soak in until the colour is uniform. Leave it to sit for a few minutes before fitting. Too much oil is worse than too little, since the excess can end up in the intake, so a light, even coat is the goal.
Seat the filter carefully so the sealing edge sits flush all the way round. A filter that is even slightly off lets unfiltered air past, which defeats the whole point. Close the lid, secure it, refit the tank and seat, and you are done.
The old filter did not go in the bin. It kept the engine clean for a long time and has earned its retirement. With the freshly oiled one in place, the K3 is breathing clean again and ready for the next season of riding.
