Sprint Filter P08 Air Filter for Road & Track – Moto Guzzi V7 III Stone (2017–2020) PM138S

Every version of the V7 III is a decision about what to add; the Stone is the one that mostly decided not to. Matt paint where the others have lacquer, no chrome to keep bright, no badge that needs polishing before it looks right. That turns out to be a useful frame of mind to carry into the airbox. Fitting the Sprint Filter P08 PM138S adds nothing at all to the motorcycle — it lifts the pleated paper panel out and puts a woven polyester one back in its place, with no coating, no bracket and no recalibration anywhere in the job.

Key Features

• Polyester weave that runs dry: no oil is applied at the factory and none afterwards
• An 80-micron aperture, quoted by Sprint Filter at 5,050 l/m²/sec of flow
• Published retention of 93.13 % against particles measured at 100 microns
• Occupies the paper panel's seat in the series airbox; the fuelling map is left alone
• About twice as much filtering area as a conventional performance panel offers
• Restored with a compressor instead of binned; two years of cover run from purchase

Subtraction, written as a specification

Filters are usually sold by what they contain — pleats, resin, a tacky coating, sometimes a second layer to catch whatever the first one let past. This one is easier to describe by what is missing. No oil, so there is no substance that can creep along the intake tract and settle where the air-mass sensor reads. No cellulose, so a damp fortnight cannot swell the medium and leave it out of shape once it dries. And no successor, because the panel that comes out of the box after a season is the panel that goes back into it.

What the small block actually registers

The 744 cc transverse twin does its work well below six thousand, on the slice of the rev range a Stone owner spends almost all of their time in. Restriction there is not theoretical: the pressure drop over a panel climbs as more air is pulled through it, so a partly loaded element charges its highest toll at the instant the throttle is opened. None of which makes the bike stronger than Mandello built it — a panel cannot do that, and anyone claiming otherwise should be read carefully. It keeps the intake close to its starting figure for very much longer than paper can.

Care and cleaning

Servicing is a compressor and five minutes. Aim the air at the clean face and drive the dirt back out the way it arrived. When a winter has left more behind than air will shift, warm water and a little washing-up liquid will lift it; keep rinsing while anything still colours the water. Then leave it standing until it is dry the whole way through, in room air only — a heat gun or a radiator will distort the weave without leaving a mark you could spot. The PM138S goes back in untreated. Sprint Filter's own written procedure is attached under Downloads.

Fitment & Compatibility

Listed for the Moto Guzzi V7 III Stone built between 2017 and 2020. Twenty-one machines share this panel — three generations of V7, both V9s, the older Nevada and three BMW singles — and the Fitment tab names each one with its build years.