Sprint Filter P08 F1-85 Air Filter for Racing – Yamaha XSR 155 (2019–2026) PM198S F1-85

The XSR 155 is a builder's motorcycle. More of them are modified than not — exhaust, intake, fuelling, bodywork — and the ones that get worked through properly end up asking their engine for rather more than it was set up to give. This element belongs at the end of that process, not at the start of it. The P08 F1-85 flows 15,000 l/m²/sec against the standard P08's 5,050, and that difference only becomes available once the rest of the intake path has stopped being the narrowest point in the system.

Key Features

• Racing medium at 15,000 l/m²/sec, roughly three times the standard P08
• Filtration to 85 microns — the wider aperture is what the flow costs
• Dry polyester, unoiled, with nothing to migrate downstream onto sensors
• A direct replacement in the standard airbox, with no modification and no remap
• Double the filtering surface of other performance filters, near enough
• Washable and reusable, brought back by compressed air on the clean side

The order in which restriction gets removed

Restriction is cumulative, and the largest term dominates everything below it. On a standard XSR 155 the filter is nowhere near that largest term, so changing it produces nothing measurable. Free up the exhaust and it moves a little closer; open the airbox path and closer again; adjust the fuelling and the engine can finally act on what arrives. Fitted in that order, the F1-85 is the last piece and it does something. Fitted first, it is an expensive way to filter slightly less well than the element it replaced.

Why the airbox is worth keeping through a build

The common alternative at this stage is an open cone filter, and it gives up more than it looks. An airbox silences intake noise, presents the engine with air at a settled temperature and pressure instead of whatever is passing the frame, and keeps water and road spray away from the intake. Replacing the fabric inside it keeps all three and addresses the one thing that was restricting flow — and it leaves the bike looking and sounding standard, which on a build that has to pass an inspection is worth something on its own. It also keeps the build reversible. Nothing about fitting this element is permanent: the box keeps its lid, its inlet, its volume and its mounting, and the original element goes back in with the same tools that took it out. On a model that changes hands often and is frequently returned towards standard before a sale, that is a practical advantage as much as a technical one.

Care and cleaning

Compressed air from the clean side, worked outwards, then refit dry. For a deeper clean use lukewarm water with a mild detergent, rinse until the water runs clear and dry it fully in air — never with heat and never with a flame. Nothing is oiled at any stage, so there is nothing to reapply after a build day. The Sprint Filter maintenance sheet is in the Downloads tab.

Fitment & Compatibility

Made for the Yamaha XSR 155 from 2019 to 2026. The same PM198S F1-85 element covers seven machines across the 125 and 155 range; the complete list is in the Fitment tab.