Sprint Filter P08 Air Filter for Road & Track – Yamaha SR400 (2013–2017) PM44S

Nothing about the SR 400 looks as though it belongs on the same shelf as a modern sports twin. It is air-cooled, it has one cylinder, and it is started with a kickstarter and a decompression lever, in a routine unchanged since 1978. What it no longer has is a carburettor. Fuel injection arrived before this fitment window opens, so there are sensors in the intake tract of a motorcycle that looks as if it predates all of that. That is the clearest argument for a dry element here: the Sprint Filter P08 PM44S is woven polyester used dry, with no oil that could travel downstream onto hardware the bike does not appear to have.

Key Features

• The P08 polyester is used dry and never oiled — nothing can migrate onto the injection sensors
• Airflow of 5,050 litres per square metre per second, with filtration at 80 microns
• About double the filtering surface of other performance filters
• Drops into the standard airbox in place of the original: no modification, no remap, homologation untouched
• Washable and reusable, designed to last as long as the motorcycle does
• Two years of warranty, running from purchase

A motorcycle that is maintained by its owner

Machines with a kickstarter tend to be kept by people who work on them. The engine sits out in the open, the side covers come away with almost no effort, and the culture around the SR is one of hand tools and weekends. A washable element suits that habit exactly: it comes out, gets blown through with an air line and goes back in, and it is still the same element several owners later.

Dry polyester, and what the numbers mean

The P08 is a single woven layer spun from polyester threads of 22 microns and upwards. Oiled cotton gauze works by making the air sticky, and that oil is a consumable sitting in the intake path; Sprint Filter measured a four-layer oiled cotton filter retaining 76.42 per cent of 100-micron test particles, against 93.13 per cent for the dry P08. Where roads are dusty or wet, finer media are woven — the P037 at 37 microns, the P14 at 14 — and each step finer costs flow: 5,050 litres per square metre per second for the P08 against 4,500 and 1,800. Finer holds more and passes less; it is a trade, not a ranking. What the P08 offers is not more power — no element in a standard airbox delivers that — but a low intake resistance that stays low.

Care and cleaning

The Sprint Filter maintenance sheet in the Downloads tab sets it out. Blow the element from the clean side outwards with an air line. Wash it in lukewarm water with a mild detergent when the air line is not enough, rinsing until the water runs clear. Dry it in open air only — no heat gun, no flame — and only refit it once it is dry right through. Do not oil it, ever.

Fitment & Compatibility

Made for the Yamaha SR 400, 2013 to 2017, and a direct replacement in the standard airbox. The same PM44S element covers four machines — this air-cooled single and three liquid-cooled twins, the YZF-R25, the MT-03 and the YZF-R3 — because the catalogue follows the airbox, not the engine. The full list is in the Fitment tab.