⟲ 360° — drag meThe facts.
DescriptionThe whole story▼
Two numbers describe an air filter, and they do not lead the same life. Filtration is the first: 80 µm for this medium, a property of the cloth itself, unchanged by anything that happens afterwards. Flow is the second: 5,050 l/m²/sec, measured on a clean element, and it begins to move the first time the engine runs. Nothing an owner does alters the first figure, and everything an owner does shows up in the second. That is the case for the Sprint Filter CM231S on a Bullet 350: a dry polyester element for the standard airbox whose flow figure is restored with an air line instead of a purchase.
Key Features
- A single woven layer of dry polyester: thread from ø 22 microns, aperture set at 80 µm
- Rated at 5,050 l/m²/sec, the medium Sprint Filter designates for road and track use
- Dry from the first fitting onwards — no oil to measure out, none to travel downstream
- About twice the filtering surface of other performance elements, inside the standard housing
- Sits where the paper panel sat: no cutting, no adaptor, no remap
- Cleaned and refitted for the life of the motorcycle, with two years of warranty from purchase
The figure that only ever climbs
A paper panel is at its most open on the day it goes in and never sees that state again. Every hour of running adds a little resistance, the rise is far too gradual to feel from the saddle, and the curve ends only when somebody buys the next one. The later part of each interval is therefore spent on the wrong side of a number printed on the box as a single value. Woven polyester differs in one respect, and it is the respect that matters here: the rise is undone rather than thrown away.
What the second figure does not buy
Not power. A drop-in element does not make a standard 350 single noticeably stronger, and a description promising otherwise has stopped describing a filter. This engine is fed by an airbox, throttle body and fuelling map signed off as a set, and the panel in the box was never the tightest point in that chain. What the CM231S offers is narrower and easier to verify: an intake resistance that returns to its starting value whenever the owner decides it should, and one line of the service list that stops repeating.
Care and cleaning
Compressed air on the clean face, worked outwards, is the whole routine most of the time. When the element is greasy rather than dusty, lukewarm water and mild detergent shift what air will not; rinse until it runs clear. Drying happens in open air and takes as long as it takes; heat guns, radiators and flame all damage polyester. It goes back in dry, with nothing sprayed on it. The maintenance sheet for the CM231S is in the Downloads tab.
Fitment & Compatibility
Cut for the airbox of the Royal Enfield Bullet 350 built from 2023 to 2026. Sprint Filter lists five machines against this element: alongside the Bullet, the Classic 350 of 2022 to 2026, the Goan Classic 350 of 2025 to 2026, the Hunter 350 of 2022 to 2026 and the Meteor 350 from 2021. All five appear in the Fitment tab; check your model year before ordering.
DownloadsOwner's manual · brochure▼
FitmentWhich bikes this fits▼
- Royal Enfield Bullet (2023–2026)
- Royal Enfield Classic (2022–2026)
- Royal Enfield Goan Classic (2025–2026)
- Royal Enfield Hunter / Hntr (2022–2026)
- Royal Enfield Meteor (2021–2026)
Questions, one topic at a time.
Get the real shipping cost for this item to your address — the same rates as checkout.
Choose a destination and hit Estimate — we fetch the live rates for this item.
We’re based in Germany. Standard delivery goes by DHL and national postal services and takes about 2–5 days within Germany, 1–2 weeks within the EU and 2–6 weeks outside the EU. Need it sooner? Express delivery reaches most of the world within a few days — just choose it at checkout where available.
Your exact shipping cost is calculated by destination and weight and shown at checkout before you pay — no hidden fees. Express delivery is selectable at checkout where available.
Yes, we ship to over 130 countries. Prices, taxes and delivery times for your destination are calculated automatically at checkout.
Within the EU, no — our prices already include all duties and EU VAT. For deliveries outside the EU (e.g. Switzerland, the UK or the USA), your order may be subject to import duties and taxes set by your country. These are collected by the carrier when your parcel arrives, aren’t included in our prices, and are outside our control.
As soon as your parcel ships we email you a tracking link, so you can follow it all the way to your door.
On out-of-stock items you can request a delivery time or leave your email to be notified the moment it returns — just use the notification box on the product.
You have the right to cancel within 14 days of receiving your order. Register your return by email first; once it’s approved you have a further 14 days to send the goods back. Items should be unused and in their original packaging.
Register your return by email with your order number before sending anything back, and we’ll send you the return instructions. Please note: returns that aren’t registered in advance can’t be accepted.
The quickest way is to place a new order for the size you need and register a return for the original by email — just let us know it’s an exchange.
We’re sorry — that shouldn’t happen. Contact us with your order number and a photo as soon as you can, and we’ll arrange a replacement or refund right away. Faulty goods are always covered by your statutory warranty.
Refunds go back to your original payment method, usually within 3–5 working days of your return reaching our warehouse.
PayPal, all major credit and debit cards (Visa, Mastercard, American Express), Klarna (pay later and instalments), Apple Pay, Google Pay and more — all processed securely via PayPal and Mollie.
Yes. Choose Klarna at checkout to split your purchase into flexible monthly installments.
Your payment is taken when you place your order. If you choose Klarna, you pay later according to Klarna’s terms.
Every payment runs over an SSL-encrypted connection through certified providers. We never see or store your full card details.
If your order hasn’t shipped yet, contact us as soon as possible and we’ll do our best to change or cancel it.
No — you can check out as a guest. An account simply lets you track orders and reorder faster.
For customers in the EU, prices are shown including your country’s local VAT. For customers outside the EU, prices are shown without VAT — instead, your country’s import taxes and duties may apply on delivery (see the customs question).
Yes. Your invoice is attached to your order confirmation email and is also available in your account.
Yes. We’re an authorised dealer, so every product is 100% original and comes with the full manufacturer warranty.
Yes. Everything we sell is genuine and comes with the manufacturer’s warranty, on top of your statutory rights. Keep your invoice as proof of purchase and contact us if you ever need to make a claim — we’ll help you through it.
Our team is happy to help. Use the contact button below and we’ll personally help you choose the right gear or part.
Measure your head circumference about one centimetre above your eyebrows and compare it with the size chart on this page. Between sizes? Choose the smaller one — the padding beds in with use.
Yes — it’s tested and approved to the current ECE 22.06 standard and road-legal across the EU.
Most of our touring and sport helmets are Pinlock-ready and many include the insert. Check the ‘What’s in the box’ section on this page for this model.
Yes — the cheek pads are channelled so the arms of your glasses slide in comfortably.
Take out the washable lining and hand-wash it in lukewarm water. Clean the shell and visor with a soft cloth and water only — never solvents.
Our team will personally help you choose the right gear or part — around 24h for a reply.