Sprint Filter P08 F1-85 Air Filter for Racing – Triumph Street Cup (2017–2026) PM174S F1-85

A Street Cup tends to belong to someone who cares about the throttle: clip-ons, a small fairing, and a habit of chasing a crisper answer from the engine. Before money changes hands, size the prize. A filter cannot make an engine breathe more freely than no filter at all; the most it can ever return is the restriction it caused itself. On a standard road machine with a sound element that is a small figure, and a medium rated at three times the air flow hands back the same small figure — not three times it. The Sprint Filter P08 F1-85 is that high-flow medium, at 85 µm against the 80 µm of the standard P08.

Key Features

• The highest-flowing woven medium in the range: 85 µm, 15,000 l/m²/sec
• A deliberate step back from the 80 µm standard P08 — the flow is paid for in retention
• About twice the filtering surface that other performance filters reach
• Dry racing polyester, never oiled, with nothing that can travel onto sensors or throttle bodies
• Drops into the standard airbox: nothing modified, nothing repositioned, nothing remapped
• Washable and reusable, with two years of warranty from purchase

The ceiling on what a filter can return

An intake tract is a series of costs paid in pressure: the duct, the box, the throttle bodies, the ports, the valves, with the element as one line on it. A freer element removes part of that line and leaves the rest where they were. That is why the honest claim for a drop-in filter is never more power. It is a low restriction that stays low across the service interval instead of drifting upwards as a cellulose element loads — and both Sprint Filter media clear that bar on a standard engine.

Where the response you are after actually lives

The transient a café-racer rider chases, that fraction of a second between opening the throttle and the engine answering, is set mostly by things standing ahead of the filter in the queue: fuelling, gearing, chain adjustment, tyre pressures and whether the element fitted now is clean. Work through those and the intake stops being the suspect. If the filter is genuinely due, the P08 at 80 µm and 5,050 l/m²/sec is the medium for road and track; on dusty back roads the P14 at 14 µm and 1,800 l/m²/sec goes further the other way. The coarser F1-85 weave belongs where an engine is opened on a schedule of operating hours and the lost filtration is a risk somebody has accepted.

Care and cleaning

Compressed air, held to the clean side and directed outwards, sends what the element caught back out the way it came. Anything left after that is a wash: water, a mild detergent, and rinsing until the water runs clear. Give the PM174S F1-85 open air until it is completely dry — no heat, no flame — and refit it dry, with no oil applied at any point. The maintenance sheet is in the Downloads tab.

Fitment & Compatibility

Made for the Triumph Street Cup, 2017–2026. 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.