Sprint Filter P08 F1-85 Air Filter for Racing – BMW R 18 (2020–2026) PM246S F1-85

Most listings for this medium end up discussing the rider: whether the throttle is ever held wide open long enough for a very high flow rating to matter. On the R 18 that discussion is settled before it starts, and not by the rider. A large, long-stroke twin of this kind makes its power low down and is built to be used there; it does not have the rev range in which an intake becomes the limiting part. PM246S F1-85 is catalogued for this machine because the housing exists, and it is worth saying plainly what that does and does not mean.

Key Features

• Racing member of the P08 family: woven polyester, dry, used unoiled
• An 85 µm aperture at a rated 15,000 l/m²/sec, the highest flow figure in the range
• Retention quoted at 95.22 per cent of 100-micron test particles
• Polyester threads from ø 22 microns, with the aperture between them doing the work
• Roughly double the filtering cloth of a typical performance element
• Direct replacement in the series airbox, cleared with air, two years of warranty

The engine decides, not the rider

A flow rating describes what a square metre of material will pass, and an engine draws on the top of it only at full throttle, high in the rev range, held there. That is a description of a sportsbike on a circuit. A twin of this size and stroke reaches its own limit long before the intake does, so the difference between the standard 5,050 l/m²/sec and this element's 15,000 is headroom the machine has no way of calling for. Nor does the wider aperture add power on this or any other motorcycle: an element inside an unmodified airbox has never done so.

If it is bought anyway

It costs a little over twice what the standard element for this housing costs, and the ratio buys a rate and nothing else. Both media are woven polyester, both are used dry, both are cleaned with air and water, both are specified for the life of the machine and both carry the same two years of warranty. Nothing separates them except the aperture and the flow figure. That is a narrow thing to pay a multiple for on a motorcycle that cannot use either number, and for almost every R 18 on the road the standard PM246S is the sensible purchase.

Care and cleaning

This element is cleaned like the rest of the family and rather more easily than most, because an open weave gives its load up readily: compressed air at the clean face, directed outward, until it runs clear. Hand-warm water and a little mild detergent are for deposits that have gone greasy, rinsed until the water is clean. Drying is by moving air alone with no heat involved at any point, since heat rather than dust is what ends these elements, and it goes back dry and unoiled. The maintenance sheet sits in the Downloads tab.

Fitment & Compatibility

Made for the BMW R 18 built from 2020 to 2026, as a direct replacement in the standard airbox. One machine is listed against this part number. The same housing also takes the standard PM246S and the 14-micron PM246P14, which between them cover ordinary road use and dusty roads. The Fitment tab shows the year span.