Sprint Filter P08 F1-85 Air Filter for Racing – Honda CB750 Hornet (2023–2026) SM247S F1-85

Read the flow figure carefully and it stops meaning what people take it to mean. Sprint Filter quotes 15,000 l/m²/sec for this racing cloth and 5,050 for the standard one, and the unit does the important work: litres per square metre per second. It is a property of the material, measured per unit of area. It is not a quantity of air, and it is not a statement about this element sitting in a CB750 Hornet's airbox. Two filters cut from the same cloth into different housings do not pass the same air; what they share is the rate at which a square metre of that material will let air through.

Key Features

• 85 µm cloth rated at 15,000 l/m²/sec, the highest rate Sprint Filter publishes
• Dry polyester throughout, never oiled, restored with compressed air
• About double the working area of a conventional performance element
• Drop-in for the standard housing: no cutting, no ducting change, no remap
• Built for the life of the motorcycle and backed by a two-year warranty
• Physically identical fit to the standard element, so the choice can be reversed at any service

A rate is not an amount

To turn that rate into a claim about a motorcycle you would need three more things: the working area of this particular element, the volume of air the engine actually demands at the revs it is used at, and the resistance of everything else in the path between the outside air and the inlet valve. None of those three is published alongside the rate, and the last of them is not a constant. What the datasheet honestly supports is a comparison between materials, which is real and useful — and nothing beyond it.

What is left after the arithmetic

Quite a lot, as it happens, but not what the number is usually recruited for. The racing line costs a little over twice the standard element for this housing, and what it delivers is a cloth specification, not an outcome. A Hornet is a road twin with a broad, mid-range engine that has no reason to press against a ceiling this high, and no drop-in filter makes a standard one noticeably stronger. Where the F1-85 belongs is a machine that spends real time near its limit — and where it does not, the standard weave was never the thing in the way.

Care and cleaning

Compressed air against the clean face handles most servicing, which is why this material suits a track weekend: it returns to the same condition without a spare in the van. When air leaves a film behind, wash the SM247S F1-85 in lukewarm water with a mild detergent and rinse until clear. Dry it in open moving air, never with heat or a flame, and refit it dry and untreated. Sprint Filter's care sheet is in the Downloads tab.

Fitment & Compatibility

Made for the airbox of the Honda CB750 Hornet built from 2023 to 2026. The racing line is catalogued against this machine, and the Fitment tab carries the entry as recorded.