Sprint Filter P08 F1-85 Air Filter for Racing – Bimota KB4 (2021–2026) PM111S F1-85

Plenty of people reach this page already running a Sprint Filter. The standard P08 element for the Bimota KB4 has the same fit, the same dry polyester construction and the same washing routine, so the racing version looks like the obvious next rung. It is not a rung. It is a move sideways, and the direction deserves to be stated plainly: the PM111S F1-85 uses the P08 F1-85 medium, which flows 15,000 l/m²/sec instead of 5,050 and filters to 85 microns instead of 80. Air flow is what you gain. Retention is what you spend to get it.

Key Features

• Dry racing polyester, filtering at 85 microns with 15,000 l/m²/sec behind it
• For road use the balanced choice is the finer standard P08: 80 microns, 5,050 l/m²/sec
• Either medium carries roughly double the filtering surface of other performance filters
• No oil is used on it, so no film migrates onto the intake sensors or throttle bodies
• Fitted in the standard airbox where the original element sat — no modification, no remap
• Washed rather than replaced, and warranted two years from the date of purchase

When the sideways move is worth making

A KB4 is not a commuter, and the argument does not have to be forced here the way it would on a touring machine. This is a small-series sporting motorcycle built around a strong four-cylinder engine, ridden on chosen days at a pace that puts the throttle wide open high in the rev range. That is precisely the operating point where a flow ceiling stops being theoretical. Ride it that way, and the extra air is at least available to be used — which is more than can be said for the same element in a bike that spends its life at a third of the revs.

The condition that comes with it

Racing filtration works because racing engines are serviced by operating hours: stripped, measured and given fresh oil far more often than any road schedule demands, so nothing the weave admitted is left to work away unseen. That is the cover for the coarser medium, and it is not optional. An owner who intends to run the KB4 on its standard mileage intervals is buying the flow without buying the protection, and the honest recommendation is to stay with the P08 — or, if the roads are genuinely dusty, to go the other way entirely to the P14 at 14 microns and 1,800 l/m²/sec. Neither choice is a downgrade. All three are the same trade set differently.

Care and cleaning

Compressed air from the clean side, directed outwards, is the routine, and the PM111S F1-85 goes back into the airbox dry. When more is called for: lukewarm water, a mild detergent, a rinse until the water runs clear, then open air until the last of the moisture has gone. Never heat, never a flame. Oiling is not part of the procedure at either end. The maintenance sheet is in the Downloads tab.

Fitment & Compatibility

Made for the Bimota KB4, 2021 to 2026. The same PM111S F1-85 element covers five machines built around this airbox, including the KB4RC and the Kawasaki models that share the engine; the complete list is in the Fitment tab.