Sprint Filter P08 F1-85 Air Filter for Racing – Royal Enfield Classic 650 (2025–2026) CM265S F1-85

The arithmetic here is unusually clean. Sprint Filter lists this racing element at exactly three times the price of the standard weave for the same airbox, and in exchange precisely one specification moves. Filtration goes from 80 to 85 microns, which is the wrong direction if protection is what is being bought. Flow goes from 5,050 to 15,000 l/m²/sec across a square metre of clean cloth. Frame, fitting position, cleaning routine, warranty and expected life are identical between the two. So the CM265S F1-85 poses a single question: does this Classic 650 ever ask a square metre of cloth for three times the rate?

Key Features

• Dry polyester racing weave with a stated filtration of 85 µm
• Rated flow of 15,000 l/m²/sec, close to three times the 5,050 of the standard medium
• 95.22 % of 100-micron particles retained in Sprint Filter's comparison measurement
• Roughly twice the filtering area of other performance elements, in the untouched series airbox
• Never oiled, cleaned with compressed air, specified to last the life of the motorcycle
• A direct replacement for the factory panel, with two years of warranty from purchase

What the multiple actually buys

Not filtration. The two cloths sit five microns apart in their ratings, and on the published comparison the coarser one scores higher, so the price ladder in this housing is not a protection ladder in any reading. What is being paid for is construction: how the racing weave is made and how much of its area is left open. That is a legitimate thing to sell and a legitimate thing to buy, but it needs saying in plain language, because a customer scanning a price column will assume the expensive element is the thorough one. Here it is the open one.

The condition that would redeem it

Capacity of this order becomes visible only under sustained wide-open throttle, held high in the rev range and repeated until the intake is the part of the machine under strain. On a road-registered Classic 650 that condition does not occur, and this page will not pretend that it does. Nor would the racing cloth change the outcome if it did: a drop-in element does not make a standard motorcycle noticeably stronger, whatever it is woven from. For ordinary use the standard 80 µm weave is the better purchase, and for dusty roads the 14 µm non-woven is the better one again.

Care and cleaning

Compressed air on the clean side of the CM265S F1-85, worked outwards until the weave is even. Water only for greasy deposits, lukewarm, with a mild detergent and a rinse until it runs clear. Then open air alone until the element is dry all the way through, with no heat gun, no oven and no flame at any point, and refit it untreated. The maintenance sheet is in the Downloads tab.

Fitment & Compatibility

For the Royal Enfield Classic 650 of 2025 and 2026. The same racing element is listed for the Shotgun 650 from 2024 and the Super Meteor 650 from 2023, three machines on one number. Check your year in the Fitment tab.