Sprint Filter P08 F1-85 Air Filter for Racing – Bimota KB4RC (2022–2026) PM111S F1-85

An air filter is the rare change that leaves no trace. Panels back on, and a Bimota KB4RC with a racing medium in its airbox looks exactly like one without. That is convenient while the bike is yours and less convenient afterwards, because the specification outlives the decision: the next owner inherits a filtration figure they cannot see, on a machine they will reasonably assume is standard inside. The Sprint Filter PM111S F1-85 filters to 85 microns and flows 15,000 l/m²/sec, where the standard P08 filters to 80 and flows 5,050. Fitting it is a considered choice. Leaving it undocumented turns that choice into someone else's blind spot.

Key Features

• The racing medium: dry polyester, 85 microns of filtration, 15,000 l/m²/sec of flow
• Set against the standard P08 at 80 microns and 5,050 l/m²/sec — coarser weave here, more air, less retention
• Both are built on roughly double the filtering surface of other performance filters
• The absence of oil means nothing can be carried downstream onto sensors or throttle bodies
• The swap is internal and fully reversible: standard airbox, no modification, no remap
• Washable and reusable, with two years of warranty running from the date of purchase

Write it down, and keep the other element

The practical answer takes five minutes. Keep the element that came out, label it with the date and the mileage, and store it with the bike's papers; note the medium and the fitting date in the service record. A machine built in small numbers is looked at closely when it changes hands, and a documented, reversible change reads as care rather than as an unknown. It also leaves the next owner free to make the same decision for themselves — the swap back is one airbox lid and no parts.

The case for fitting it at all

There is one, and it is stronger here than on most road bikes. A KB4RC is ridden in short, chosen, hard sessions rather than commuted on, and wide throttle high in the rev range is the only place a flow figure of 15,000 l/m²/sec can be collected. The condition is the same one every racing medium carries: it belongs on an engine serviced by operating hours, opened and given fresh oil on a racing rhythm, because that is what accounts for the material an 85-micron weave lets past. Run to standard road intervals, the coarser medium is a cost without its cover, and the P08 is the element to buy instead.

Care and cleaning

Cleaning it is a short list. Compressed air from the clean side, blown outwards; a wash in lukewarm water with a mild detergent when conditions have earned one; a rinse until the water runs clear; then open air, never heat and never a flame, until the element is dry. Refit it in that state. At no point in its life does the polyester get oiled. The maintenance sheet is in the Downloads tab.

Fitment & Compatibility

Made for the Bimota KB4RC, 2022 to 2026. The same PM111S F1-85 element covers five machines built around this airbox, including the KB4 and the Kawasaki models sharing the engine; the complete list is in the Fitment tab.