Sprint Filter P08 F1-85 Air Filter for Racing – Triumph Street Twin (2016–2026) PM174S F1-85

One published figure looks at first glance like an argument for this filter, so it is better dealt with here than left to work quietly in the background. In Sprint Filter's own comparison the F1-85 retains 95.22 % of 100-micron particles, where the standard P08 retains 93.13 %. Read both carefully: they describe how each weave copes with particles of one particular and rather large size. What separates the media is the aperture, and there the F1-85 sits at 85 µm against the P08's 80 µm. A wider aperture cannot hold back more of what is small enough to travel through it.

Key Features

• 85 µm at 15,000 l/m²/sec, where the standard P08 sits at 80 µm and 5,050 l/m²/sec
• The three-fold flow is paid for with a coarser weave — that is the trade, stated plainly
• Filtering surface: roughly double that of other performance filters
• Dry racing polyester, never oiled, so no film can migrate onto the air sensor
• Goes into the standard airbox as a direct replacement — no modification, no remap
• Compressed air is the service; washable, reusable, and covered for two years

Which particles are the ones that matter

Anything large enough to see is stopped by more or less any filter, which is why a comparison run at 100 microns flatters every medium in the test. Engine wear is done by the fine mineral fraction — small enough to stay suspended, follow the airstream through the ports and end up between a ring and a bore or circulating in the oil. Those are the sizes at which five microns of extra aperture change something, and they are exactly the sizes the headline percentages say nothing about.

What this motorcycle is more likely to be doing

If the Street Twin is the bike that goes to work, its air diet is traffic: brake and tyre abrasion, road grit ground fine by everything ahead of you, a slow drizzle of particles that never makes an element look dramatically dirty. That argues for retention rather than flow, and a mild twin at commuting revs never comes close to drawing what the standard medium can pass, let alone 15,000 l/m²/sec. For year-round road use the P08 at 80 µm and 5,050 l/m²/sec is the sensible default; where dust is a real feature of the route, the P14 at 14 µm and 1,800 l/m²/sec goes further still. Finer retains more and flows less — a trade, not a ranking.

Care and cleaning

Hold compressed air to the clean side of the PM174S F1-85 and blow outwards, so what the weave caught leaves along the path it entered by. Water and a mild detergent deal with the remainder; rinse until the water runs clear. Dry the element fully in open air, keeping heat and flame away from it entirely, and refit it dry — there is nothing to oil. The maintenance sheet is in the Downloads tab.

Fitment & Compatibility

Made for the Triumph Street Twin, 2016–2026. The same element covers five machines built around this airbox — the Bonneville T100 and T120, the Street Cup, the Street Scrambler and the Street Twin. The full list with model years is in the Fitment tab.