Sprint Filter P08 F1-85 Air Filter for Racing – BMW R 1250 RT (2019–2023) PM142S F1-85

The obvious thing to say about a racing weave on a full-dress tourer is that it has found the wrong motorcycle, and the obvious thing is very nearly right. Where it is wrong is the interesting part. Sustained wide throttle high in the rev range is a circuit condition; the closest a public road ever comes to it is a heavily loaded machine dragging itself up a long mountain pass in a low gear on a hot afternoon, minutes at a time. Of the three motorcycles listed for this element, the RT is the one that actually does that.

Key Features

• Dry woven polyester opened to 85 microns, the most open cloth Sprint Filter makes
• Rated flow of 15,000 l/m²/sec, where the standard element for this box carries 5,050
• Measured retention of 95.22 per cent against 100-micron test particles
• Filtering surface roughly twice that of an ordinary performance element
• Exchanged straight for the factory panel in the standard housing, with no remap
• Serviced with compressed air, specified for the machine's life, two years of guarantee

The nearest a road gets

An alpine pass with a passenger, luggage and a top box is not a track session, but it is the only everyday situation in which a big touring boxer is held near the top of its range for minutes rather than seconds. That is the shape of demand the 15,000 l/m²/sec figure was written for, and a tourer meets it rather more often than a roadster does. It is worth finishing the sentence, though: even up there, nothing suggests the standard element runs out. A rated 5,050 l/m²/sec is a very large figure for a twin of this size at the revs it turns, and on a pass the limits that bite are heat, gearing, mass and the rider's patience.

What is really being bought

A capacity, and only that. The element is listed at close to three times the standard weave for this airbox, while everything else on the specification is shared: dry polyester carrying no oil, a fit that needs no cutting and no remap, an air line in place of an annual purchase, a design life matched to the motorcycle's own, two years of cover. Neither of them is a power part. An element inside an unmodified airbox does not make a standard R 1250 RT noticeably stronger, and paying more for a more open cloth changes nothing.

Care and cleaning

Take the element out, put a compressor line on the face that looks towards the engine and work outwards until the cloth is clear; that is a normal service from beginning to end. Long summers leave a film that air stops removing, and then it is tepid water with a mild detergent and a rinse carried on until the water is clean. Drying takes as long as it takes, in moving air alone: no heater, no oven, no flame, all of which ruin polyester permanently. The PM142S F1-85 goes back dry and unoiled; the maintenance sheet is filed under Downloads.

Fitment & Compatibility

Made for the BMW R 1250 RT of 2019 to 2023, seated in the standard airbox without modification. Three machines carry this part number — the R, the RS and the RT, all of the 1250 generation — and each is listed with its years in the Fitment tab.