Sprint Filter P08 F1-85 Air Filter for Racing – BMW F 900 XR (2019–2026) PM188S F1-85

Sport-tourers get ridden in the rain, and an airbox is designed on that assumption. BMW puts the intake mouth where spray is least likely to reach it, seals the box and gives whatever does get in somewhere to leave again. The filter's own part in all that is easy to skip over when a specification is being read for flow figures, so it is worth asking what an open racing weave actually does with water before an F 900 XR spends a winter with one fitted.

Key Features

• Polyester, woven, run dry — nothing oiled, so nothing that rain can wash downstream
• 85 µm between the threads with 15,000 l/m²/sec of rated flow, Sprint Filter's racing figure
• Roughly twice the surface of a typical performance element, in the standard frame
• An exact replacement for the factory panel, with the box and the mapping left alone
• Washable with water and detergent as a matter of routine, not of risk
• Guaranteed for two years from purchase

What a dry weave does when it gets wet

A soaked element is a restricted element whatever it is made of, because water standing in the openings is not air passing through them. The difference lies in what happens next. Paper takes water into its structure and can lose its shape doing so; oiled cotton carries a film that rain slowly moves somewhere it was never meant to go. This cloth does neither. It holds no oil to lose, and it dries — the same property that makes it washable at all, and why a wet ride is a non-event rather than a service item. What no dry weave does is repel water — Sprint Filter builds a separate medium for that, the P037, closed to 37 µm and treated to shed it, flowing 4,500 litres per square metre per second because that is the price of the treatment.

The XR's real question

Which leaves a choice between two dry weaves, and for a machine that covers distance on sealed roads in every kind of weather the racing one is hard to justify. Its 15,000 litres exist for engines held near maximum revs at full throttle for minutes together; a sport-tourer at motorway speed uses a modest share of its available airflow, in top gear, well short of the limiter. Nothing in that day approaches the ceiling. The standard P08 offers the same dry cloth, the same washability and the same generous surface, while the F1-85 asks roughly two and a half times as much for capacity that stays unused. Buy the racing element for circuit work, not for weather.

Care and cleaning

Compressed air first, from the clean face of the PM188S F1-85 and directed outward. After a wet season a wash is sensible: lukewarm water, a mild detergent, and a rinse that carries on until the water leaves clear. Then the slow part — drying in open air, with no heat applied and no flame nearby, until no moisture is left anywhere in the weave. Only then does it go back in. The maintenance sheet is filed under Downloads.

Fitment & Compatibility

Listed for the BMW F 900 XR from 2019 to 2026, seated in the unmodified airbox. Nine machines share this racing element between BMW's middleweight F range and Kove; the Fitment tab has the complete list.