Sprint Filter P08 F1-85 Air Filter for Racing – Royal Enfield Guerrilla 450 (2024–2026) CM274S F1-85

Four grades share this airbox, and the distance between the ends of that range is easy to underestimate. The extreme grade is rated at 560 l/m²/sec; this one, the racing weave, at 15,000 — close to twenty-seven times as much through the same size of opening. Nothing about a range that wide reads as a ladder with a best rung at the top. It reads as a span, with two opposite jobs at its ends and the ordinary road element sitting nearer the middle. The CM274S F1-85 is one end of that span, and picking it is a decision about use, not about rank.

Key Features

• Dry polyester racing weave rated at 85 µm with a flow of 15,000 l/m²/sec
• Coarser in rating than the 80 µm standard element, and roughly three times as free-flowing
• Retention measured at 95.22 % of 100-micron particles in Sprint Filter's comparison
• Roughly twice the filtering surface of other performance elements, in the untouched airbox
• Fits the series box exactly as the standard element does — nothing cut, no remapping
• Washed and reused rather than replaced, with two years of warranty from the purchase date

A span, not a ladder

Ranges of filters are usually presented as a progression, which is why buyers reach for the top of the list and expect it to be the best of the four. Here the arithmetic refuses that reading. Going one way from the standard weave gives more retention and less flow; going the other way, to this element, gives more flow and a coarser rating. Both directions cost something, and neither is an improved version of the middle. What resolves it is the job the machine is given on the days that matter, and for most Guerrillas that answer points at the middle of the span.

The condition this grade answers

The flow figure is a rate for a square metre of clean cloth, and it is called upon only where an engine is held near full throttle for long, repeated stretches with the intake as the limiting factor. That is a description of track use rather than of any road, and it is worth saying that plainly before the order rather than after it. What no version of this element does is make a standard machine noticeably stronger — nothing dropped into an unmodified airbox does that. On a road bike the visible effect of the racing weave is a longer stretch between airbox visits, since a coarser cloth loads more slowly than a fine one.

Care and cleaning

Air on the clean face, directed outwards, is the routine for the CM274S F1-85 as it is for every element in the range. Greasy deposits come off with lukewarm water and a mild detergent, rinsed until the water runs clear. The drying is where the rated flow is won or lost: room-temperature air, moving if possible, all the time it needs, and never a heat gun, an oven or a flame. A damp element refitted in a hurry gives away exactly what it was bought for. The maintenance sheet is under Downloads.

Fitment & Compatibility

For the Royal Enfield Guerrilla 450 of 2024 to 2026. The Himalayan 452 of the same years is listed against the same element, two machines in total. Check your year in the Fitment tab before ordering.