Sprint Filter P08 F1-85 Air Filter for Racing – Kawasaki Ninja 400 / EX 400 (2018–2026) PM164S F1-85

No small motorcycle of the last decade has filled more grids than the Ninja 400, and that is the context this element was built for. It is also the reason to be careful about what is claimed for it. On a dynamometer, a freer-flowing intake on a prepared engine produces a number. On a stopwatch, at the speeds a 399 cc twin reaches on a club circuit, that number is buried under corner speed, gearing and the rider. The P08 F1-85 flows 15,000 l/m²/sec against the standard P08's 5,050 — a real difference in the part, and an honest description of it stops short of promising a result.

Key Features

• Washable and reusable, cleaned with compressed air from the clean side — a single purchase rather than a season of them
• Racing medium at 15,000 l/m²/sec, roughly three times the flow of the standard P08
• Filtration to 85 microns; the wider aperture is what the flow is bought with
• The filtering surface comes to roughly double that of other performance filters
• Dry polyester, never oiled — no oil film for a sensor or a scrutineer to find
• Fits the standard airbox — no modification and no remap needed to install it

A season, not a session

The argument that survives contact with a real race programme is the running cost one. A grid bike gets through air filters in a way a road bike does not — gravel dust, paddock traffic, a van, and a meeting every few weeks. A washable element turns that recurring line into a single purchase: blown through between sessions, washed at the end of a meeting, and used again the following spring. Over a season that is worth more to a privateer than any dyno graph, and it is the part of the case that does not depend on how the bike is prepared.

The change that stays inside the box

The Ninja 400 also has one of the busiest aftermarkets in motorcycling, much of it involving intake parts that are visible, audible or both. This element is none of those things: the airbox keeps its lid, its inlet, its volume and its mounting, and the only thing that changes is the fabric inside. Nothing is declared, nothing is remapped, and the original element can go back in an afternoon. Whether that satisfies a particular set of class regulations is a question for that rulebook — but the description above is precise, and it is what a rulebook needs to be read against.

Care and cleaning

Between races, compressed air is enough: clean side, blow outwards, refit dry, and the element is back in the box before the tyre warmers are off. Gravel dust and a long weekend justify more — lukewarm water with a mild detergent, a rinse until the water runs clear, then a full air dry somewhere out of the way. Not with heat and not near a flame; that shortcut costs the element. There is no oiling step. The Sprint Filter maintenance sheet is in the Downloads tab.

Fitment & Compatibility

Made for the Kawasaki Ninja 400 and EX 400 from 2018 to 2026; both designations describe the same machine. The same PM164S F1-85 element covers eleven machines around this airbox; the complete list is in the Fitment tab.