Sprint Filter P08 F1-85 Air Filter for Racing – Honda Monkey 125 (2018–2026) PM179S F1-85

This page needs to start with the awkward part. The F1-85 is the most expensive element Sprint Filter makes for this airbox — several times what the standard P08 costs for the very same fitment — and it is being offered here for a 125 whose entire character is modesty. Most Monkey owners should buy the P08 and stop reading. What follows is the narrow case in which this one is not an absurd purchase.

Key Features

• Racing-specification dry polyester: 85 µm at 15,000 l/m²/sec
• The highest flow rate in the Sprint Filter range, roughly three times that of the P08
• 95.22 % retention of 100-micron particles, against 93.13 % for the P08
• Fits the series Monkey airbox unmodified — no cutting, no remap
• Dry throughout: cleaned with compressed air, never oiled
• Made to last the life of the machine, with two years' warranty from purchase

Coarser and cleaner at the same time

The obvious reading of 85 µm against the P08's 80 is that you are buying less filtration for more money. The measured figures say otherwise: the F1-85 retains 95.22 per cent of 100-micron particles where the P08 retains 93.13, and it flows about three times as much air. It is not a P08 with the mesh opened up; it is a different specification that happens to beat it on both counts. The reason it is still the wrong default is cost, not capability.

When it makes sense on a Monkey

Not for the flow. A 125 will not reach 15,000 l/m²/sec in this lifetime or the next, and a drop-in filter does not make a standard Monkey quicker in any case — nothing fitted to a standard airbox does. The honest argument is the retention figure and the fact that this element, like every Sprint Filter, is bought once. If you keep the machine indefinitely, ride it in genuinely dirty air, and want the highest retention available for this housing, the PM179S F1-85 delivers it. If you are choosing on price or on performance, the P08 is the right answer and this is not.

Care and cleaning

Blow it through from the clean face outwards with compressed air. Water and a little mild detergent handle anything greasy; rinse it until the water runs clear, then let it dry fully in moving air. Heat of any kind ruins polyester, so no heat guns, radiators or flame, and it is refitted dry and untreated. The maintenance sheet for the PM179S F1-85 is in the Downloads tab of this page.

Fitment & Compatibility

The P08 F1-85 element for the Honda Monkey 125, model years 2018 to 2026. One machine, one airbox, and the same housing that takes the P08 and the P14 — the medium is the only variable. Order by element code and model year.