Sprint Filter P08 F1-85 Air Filter for Racing – BMW R nineT Racer (2017–2020) PM109S F1-85

The standard element for this airbox is listed against fifteen motorcycles. The racing weave in the same frame is listed against one, the R nineT Racer, and that narrowing is the most informative thing on the page. Sprint Filter did not offer this specification to the roadster, the Pure, the Scrambler or the older boxers sharing the housing. It offered it to the single variant BMW built low, with a fairing and clip-on bars.

Key Features

• Dry woven polyester, the racing member of the P08 family, used without oil
• An aperture of 85 µm at a rated 15,000 l/m²/sec, the highest flow figure Sprint Filter publishes
• Retention quoted at 95.22 per cent of 100-micron test particles
• Threads from ø 22 microns across, with the openings between them doing the filtering
• Around twice the filtering cloth of a typical performance element
• Goes into the series airbox where the paper panel sat: nothing cut, no remap

What a one-line list means

It is a statement of intent, not of fit. The housing is shared, so this panel would seat in a Pure or a Scrambler exactly as it seats here; the catalogue is saying that only one of those machines is sold to riders expected to want it. The Racer is the version whose owners take it to open days and circuits, and a high flow rating is only ever collected there. It is not a homologation, not a race entry and not evidence about the engine, which is the same air- and oil-cooled twin underneath.

The condition, and who meets it

A flow figure describes what a square metre of material will pass, not a quantity delivered to an engine, and its top is reached only with the throttle fully open, high in the rev range, held for whole seconds at a time. On the road that state survives a fraction of a second between gearchanges. A twin with a wide, flat spread of torque does not live at its rev limit even on a circuit, so most owners will call for this rating rarely if ever. Nor does the wider aperture add power — nothing inside a series airbox does — and the standard 80 µm weave at 5,050 l/m²/sec passes everything a road ride asks for.

Care and cleaning

Servicing PM109S F1-85 is dry work in the ordinary case: an air line held to the clean face and directed outward until the weave is clear. Where a film has built up that air will not take, hand-warm water with mild detergent will, rinsed until clean. Drying happens in moving air and nowhere near a heat source, because heat rather than dust destroys the medium, and the element returns to the box dry — the same routine between two sessions as at the end of a season. The maintenance sheet is under the Downloads tab.

Fitment & Compatibility

Made for the BMW R nineT Racer of 2017 to 2020, as a direct replacement in the standard airbox. The fitment list holds this machine alone. Owners of the other boxers on this housing — the R nineT, the Pure, the Scrambler and the older R 1200 and HP2 models — will find them on the standard PM109S, with the fine PM109P14 for the Scrambler and the 7-micron PM109T12 for the GS and HP2 side of the range. The Fitment tab has the detail.