Sprint Filter P08 F1-85 Air Filter for Racing – Kawasaki ZX-4R (2023–2026) PM164S F1-85

The ZX-4R is the road-going member of a pair whose other half goes racing, and buyers of the two often want the same parts. On air filters that instinct deserves a second look, because the racing medium is the only Sprint Filter fabric that filters more coarsely than the standard one. The P08 F1-85 works at 85 microns where the P08 works at 80, and it buys about three times the air flow with that difference: 15,000 l/m²/sec against 5,050. Whether that is a good bargain depends entirely on where the bike is ridden and how often the engine is opened.

Key Features

• Roughly double the filtering surface of other performance filters, measured across the panel
• Dry polyester with no oiling step — nothing to migrate onto sensors or throttle bodies
• Racing medium: air flow 15,000 l/m²/sec, filtration 85 microns
• Built to last the life of the motorcycle, and warranted for two years
• The standard airbox takes it as a direct replacement, with no modification and no remap
• Washable and reusable — cleaning it means compressed air from the clean side

Filtration is not a detail on a road bike

A circuit is a swept surface used by a small number of prepared machines, and a public road is neither. Fine airborne material — brake and tyre particulate, field dust, construction traffic — is present continuously on the road and is exactly the size range where a slightly wider aperture matters. A race engine can accept that because it will be stripped long before anything accumulates unseen; a road engine expected to run for years without being opened cannot. This is the whole reason the standard P08 exists as the road and track medium, and why the P14 at 14 microns exists beyond it.

When the ZX-4R is the right bike for it

The honest case is a ZX-4R used mainly on track, or one whose intake and exhaust have already been opened up and mapped, where the engine can finally act on the extra air and the service schedule has moved to a racing one. In that condition the F1-85 is the correct part and the coarser weave is a considered decision rather than an overlooked one. Bought for a standard road-ridden ZX-4R, it is an expensive way to filter slightly less well — and the element it should be compared against is the P08, not the price.

Care and cleaning

Compressed air is the routine and it is worth doing before the bike is asked for anything: from the clean side, directed outwards, then refit the PM164S F1-85 dry. When it needs more than air, lukewarm water and a mild detergent do it, followed by a rinse until the water runs clear and a full air dry — never with heat, never near a flame. Whichever of the three media is fitted, none of them is ever oiled. The Sprint Filter maintenance sheet is in the Downloads tab.

Fitment & Compatibility

Made for the Kawasaki ZX-4R from 2023 to 2026. The same PM164S F1-85 element covers eleven machines built around this airbox; the complete list is in the Fitment tab.