Sprint Filter P08 F1-85 Air Filter for Racing – Indian Challenger Limited (2020–2026) PM237S F1-85

This element filters in one layer. There is no second stage behind the first and no thickness of matting for something to be caught in on a later pass: whatever the weave does not stop at its face has gone through. Layered gauze works the other way, staging capture across several thicknesses. Neither approach is automatically the better one, but the single plane explains a good deal about how this filter is made, how it measures, and what cleaning it actually needs.

Key Features

• One layer of woven polyester, dry from manufacture and never oiled
• Rated 85 microns with a flow figure of 15,000 l/m²/sec, the most open medium listed here
• 95.22 % of 100-micron particles retained in the manufacturer's published comparison
• Fits the standard airbox exactly as delivered, without modification or remapping
• About twice the filtering surface of other performance elements, in the original frame
• Serviced with compressed air, designed to last the machine, two years of warranty

Everything happens at the surface

A single weave has to hold its aperture evenly, because there is nothing behind it to cover for a loose patch, and that is where the manufacturing effort in a racing cloth goes. It also means the load stays where it can be reached. Dust sits on the face instead of working itself into a depth of fibres, so an air line recovers most of it and the element returns close to the condition in which it left the box. A filter that can be brought back to a defined state is worth more to an owner who opens the airbox often than one whose condition drifts quietly.

The trade behind the flow figure

Fifteen thousand litres per square metre per second is a rating for clean fabric, and it is had by leaving the aperture at 85 microns rather than closing it down. Where air carries a constant fine load, this same housing is catalogued with a 14-micron nonwoven rated 1,800 — the opposite decision, taken for opposite conditions. Neither is a grade above the other. And neither turns a standard Challenger Limited into a faster motorcycle: a panel inside an unaltered airbox has no mechanism for that. It holds intake resistance low, and that figure can be restored indefinitely.

Care and cleaning

Compressed air applied from the clean side of the PM237S F1-85 outwards is the whole routine most of the time. When a season has left something air will not shift, lukewarm water and a mild detergent will, with a rinse until the water leaves clear. Drying happens in moving air at room temperature and by no other means: radiators, hot-air guns and flames damage the fibres before any change is visible. The weave goes back into the airbox dry and untreated. Downloads holds Sprint Filter's maintenance sheet.

Fitment & Compatibility

Made for the Indian Challenger Limited of 2020 to 2026. The Challenger and the Challenger Dark Horse are listed against the same part number over the same model years, so three machines share one code. Confirm your year in the Fitment tab before ordering.