Sprint Filter P08 Air Filter for Road & Track – Triumph Bonneville Bobber (2017–2021) SM225S

A Bonneville Bobber has one seat, and that is a specification as much as a styling decision. The machine carries its rider and nothing else — no passenger, no panniers, no touring load — so the work it asks of the engine is settled on the day it leaves the factory and never changes afterwards. That makes the air side of this motorcycle unusually simple to think about. Engine, airbox and workload are all fixed; the single quantity in the intake that drifts over the years is the restriction of the element sitting inside it. The Sprint Filter SM225S is the dry woven polyester version of that element: cleaned with an air line, refitted, and not bought again.

Key Features

• One woven layer of dry polyester, threads from ø 22 microns, aperture calibrated to 80 µm
• Rated at 5,050 l/m²/sec — the medium Sprint Filter designates for road and track use
• Never oiled, so no film can migrate downstream onto the air sensor or the throttle bodies
• Roughly twice the filtering surface of other performance elements, inside the standard airbox
• A direct replacement for the paper panel: no airbox modification, no remap, no paperwork
• Washable and reusable, built to last the life of the motorcycle, two years of warranty from purchase

Why the standard medium is the finished answer here

Sprint Filter makes finer media than this one, and it is worth saying plainly why the Bobber does not want them. A P14 non-woven holds back down to 14 µm but flows 1,800 l/m²/sec; a T12 reaches 7 µm at 560. Finer structure retains more and passes less — a trade, not a ranking, and one worth making only where the air is genuinely bad. A solo road machine on sealed surfaces never puts that question. The P08 is where this bike belongs, with no upgrade waiting further down the list.

What it changes, and what it does not

Not the power. A drop-in element cannot make a standard 1200 twin noticeably stronger, and any description promising that has stopped describing a filter. What changes is the part of ownership between services. A paper panel starts at its lowest restriction and climbs from there until somebody buys the next one, so the worst air path of every interval is its final stretch. A washable element comes out, gets cleaned and goes back whenever the owner decides — and the repeat purchase leaves the list.

Care and cleaning

Routine service for the SM225S is compressed air on the clean side, blown outwards through the media. After a hard season, wash it in lukewarm water with a mild detergent and rinse until the water runs clear. It dries in open air only — never with heat, never with a flame — and goes back into the airbox dry. No stage of that involves oil. The maintenance sheet is in the Downloads tab.

Fitment & Compatibility

Made for the Triumph Bonneville Bobber built from 2017 to 2021. The same element also covers the Triumph Bonneville Speedmaster of 2018 to 2021, which shares this engine and airbox — two machines on one part number. Confirm your model year in the Fitment tab before ordering.