Sprint Filter P08 Air Filter for Road & Track – Honda GB350C (2024–2026) SM289S

The C sits its rider lower and further back than the rest of the family, and that stance changes the way the engine is worked. A machine set up this way carries a pillion more often, carries luggage more often, and gets ridden a gear higher than it strictly wants to be — long stretches at high load and low revolutions rather than short bursts at speed. Load is the condition that matters to an air filter, not velocity. A 350 cc single pulling two people up a long gradient is drawing as much air as it ever will, at the point in the rev range where it has least to spare. The Sprint Filter P08 SM289S will not make that gradient shorter, because no drop-in element does. It keeps the restriction ahead of the throttle body from creeping upward between services.

Key Features

• About double the filtering area of other performance elements, and a rated flow of 5,050 l/m²/sec
• Its polyester threads begin at ø 22 microns, woven to a calibrated aperture
• Dry throughout, never oiled, so nothing is carried downstream to the sensors
• Standard airbox, standard position, standard map: no modification, no remap, homologation untouched
• Washed and blown through rather than reordered — what comes out goes back in
• Built to serve for as long as the motorcycle does

An engine with no surplus to lend

On a large-capacity machine a slowly loading filter disappears into the reserve: enough output that a few per cent of extra pressure drop goes unnoticed and the rider blames the weather. A 350 has no such cushion. Whatever the filter takes comes out of a modest total, and it is taken hardest under exactly the conditions the GB350C is built for — sustained load, low revolutions, wide throttle. This is not a claim that a filter adds power, because it does not. It is that the loss you can prevent counts for more on a small engine, and preventing it means a medium that can be returned to its starting condition rather than one that only ever gets worse.

Two people, luggage, and the interval that follows

Riding fully laden also changes the servicing question. The bike does more work per kilometre, the airbox sees more air per kilometre, and the element ages by the volume of air that has crossed it rather than by the odometer. Distance-based intervals are a rough approximation of that and nothing more. With a washable element the answer is to look: pull it out, hold it to the light, blow it through if it needs it, refit it.

Care and cleaning

The normal service takes a compressor: clean side first, blowing outwards, so what the element caught leaves by the face it came in through. When the riding has been hard on it, wash the SM289S in lukewarm water with a mild detergent and rinse until the water runs clear. Then open air, no heat and no flame anywhere near it, and refit only once it is dry. There is no oiling stage. The maintenance sheet is in the Downloads tab.

Fitment & Compatibility

Made for the Honda GB350C from 2024 to 2026. The same SM289S element covers five machines built around the same 350 cc single; the complete list is in the Fitment tab.