Sprint Filter P08 F1-85 Air Filter for Racing – Zontes ZT 350-GK (2020–2026) SM277S F1-85

The catalogue runs this model to 2026, so some of these machines are only weeks old. A fresh engine is at its most sensitive to abrasive material while rings and bores are still bedding to one another, and that happens to be the same window in which a pleased new owner is most likely to be shopping for parts. The two facts sit awkwardly together when the part under consideration is the most open medium in the range.

Key Features

• Dry polyester in racing specification, filtering at 85 µm with 15,000 l/m²/sec of rated flow
• Coarser than the standard element for this airbox, which is rated at 80 µm and 5,050 l/m²/sec
• Retention measured at 95.22 % on 100-micron particles; oiled four-layer cotton returned 76.42 %
• Replaces the original panel in the unmodified series housing, with no adaptor and no remapping
• About twice the filtering surface of a typical performance element
• No oil at any stage; cleaned and refitted for the life of the machine, two years of warranty

The worst-timed version of this decision

Fitting the most open cloth available to an engine that has not finished bedding in is the least attractive order in which to do things. The surfaces are still conforming to one another, the debris of that process is still being carried away by the oil, and whatever the intake contributes arrives at the least helpful moment. None of this is dramatic — a medium rated at 85 µm is a filter, not an open trumpet, and its measured retention on coarse dust is the highest figure Sprint Filter publishes. But the case for opening the weave has to be strong, and on a barely used road motorcycle it is not.

What a new ZT 350-GK actually wants

The standard element: fitted whenever suits the owner, washed at every convenient service, and otherwise left alone. It costs a fraction of the racing cloth, filters to 80 µm and flows 5,050 l/m²/sec, which is comfortably more than this capacity asks for. In every other respect it is the same dry, reusable, directly fitting part. Should the machine later become a track bike, the racing medium will still be catalogued under this housing code and will still go straight in — and a slot-in element makes a standard motorcycle no quicker either way.

Care and cleaning

Use an air line on the clean face, working outward, so that the load is expelled rather than driven further in. If the element has gone greasy, lukewarm water with a mild detergent will free it, and the rinse continues until the run-off carries nothing more. Drying takes place in moving air at room temperature and under no circumstances with heat or a flame, and the SM277S F1-85 is refitted only when the material is thoroughly dry, with nothing added to it. The maintenance sheet is in the Downloads tab.

Fitment & Compatibility

Listed for the Zontes ZT 350-GK, model years 2020 to 2026. The same element serves eight other Zontes entries, from the 250 of 2019 to 2021 up through the rest of the 350 range. Nine catalogue lines, a single code.