Sprint Filter P08 F1-85 Air Filter for Racing – Triumph Rocket 3 (2019–2026) PM233S F1-85

A rated flow figure is a ceiling, and ceilings only matter to engines that go near them. The interesting question for the Rocket 3 is not whether 15,000 l/m²/sec is a large number — it is — but how much of this motorcycle's working life is spent anywhere close to needing it. A long-stroke triple of this size makes its case at the bottom of the rev range and is geared to stay there; the top of the airflow curve is territory it visits briefly, if at all. Headroom bought for that territory is headroom bought for a few seconds a year.

Key Features

• Dry polyester racing medium: 85 µm rating at 15,000 l/m²/sec
• Roughly three times the rated flow of the standard P08, on a slightly coarser weave
• Measured at 95.22 % retention of 100-micron particles, against 93.13 % for the P08
• Never oiled — nothing to apply and nothing to carry downstream
• Fits the standard airbox in the original position, with no modification to the housing
• Cleaned with compressed air and refitted; two years' warranty from the date of purchase

Where a flow ceiling is actually reached

Peak intake demand happens at wide throttle and high engine speed, and it is momentary even on machines built for it. Everything else — town riding, cruising, the long third-gear roll that this engine exists for — sits well below the ceiling, where the difference between one medium and another cannot express itself. Retention, by contrast, applies to every litre of air that passes, in every one of those conditions. That asymmetry is the reason the PM233S F1-85 reads as a specialist item on a road-going Rocket 3 rather than as a general improvement over the standard element.

Who the coarser weave is for

It is for engines that have been changed until they ask for more air than the standard specification supplies, and for machines serviced on a competition schedule, where a little extra fine dust is settled at the next rebuild. By Sprint Filter's own account this class of medium is the most widely used in MotoGP, Moto3, World Superbike, Supersport and Superstock — the manufacturer's own claim rather than an independent count, but consistent with that reasoning. On a standard machine it adds no power, because nothing fitted to an unmodified airbox does; it moves the balance towards flow and away from filtration.

Care and cleaning

Compressed air from the clean side outwards, so the dust exits by its entry route. Lukewarm water with a little mild detergent when air alone will not do, rinsed until the water runs clear. Never dry it with heat, a hot air gun or a flame, and never refit it damp or treated with anything. Cleaned this way it returns to the same starting restriction every time. The maintenance sheet for the PM233S F1-85 is in the Downloads tab of this page.

Fitment & Compatibility

The F1-85 element for the Triumph Rocket 3, model years 2019 to 2026, R and GT alike. The same standard airbox also accepts the P08 and the fine P14, so a change of medium later costs nothing but the element itself.