K&N BM-1821 High-Flow Air Filter for 2020-2025 BMW R18 Series

Vehicle Fitment

• 2020-2025 BMW R 18 / R 18 Classic / R 18 B / R 18 First Edition / R 18 Transcontinental / R 18 Roctane / R 18 100 Years (1802 cc)

Features

• Pleated multi-layer cotton-gauze media for increased airflow and effective filtration
• Washable & reusable - reduces recurring filter replacement cost and waste
• Pre-oiled and ready to install from the box
• Application-specific sealing bead for precise fit in OEM air box
• Large filtration surface area for stable airflow under load and improved throttle response
• Designed to boost performance (horsepower/acceleration) vs stock filter
• Drop-in replacement - no modifications or fuel-management changes required
• Backed by K&N's No-Hassle Lifetime Limited Warranty

Specifications

• Filter shape: Panel
• Material: Cotton gauze (pleated multi-layer)
• Outside length: 8.938 in (≈ 227 mm)
• Outside width: 4.938 in (≈ 125 mm)
• Height (thickness): 0.844 in (≈ 21 mm)
• Weight: approx. 0.5 lb (≈ 0.2 kg)
• Filter re-oil amount: 0.42 oz (≈ 12 ml)
• Washable / reusable: Yes

Included Components

• 1x High-flow panel cotton-gauze air filter (pre-oiled)

Product Description

The K&N BM-1821 is a precision-engineered replacement air filter tailored for the modern 1802 cc BMW R 18 family (R18, R18 Classic, R18 B, R18 Transcontinental, R18 Roctane and special editions) from model years 2020 through 2025. Its pleated cotton-gauze media significantly increases airflow compared to standard paper filters, while retaining high filtration efficiency to protect your engine from dust and contaminants. The larger filtration surface helps ensure smoother throttle response, improved engine breathing, and potentially better engine performance - especially useful for touring, daily riding, or performance-oriented use.

Installation is simple and straightforward: BM-1821 is a direct, bolt-in replacement for the original filter - it drops into the stock airbox with no need for modifications or fuel-management tuning. Because it is washable and reusable, the filter can be cleaned, re-oiled, and reused multiple times, which offers long-term cost savings and sustainability. Backed by K&N's lifetime-limited warranty, the BM-1821 is a durable, performance-oriented upgrade for any BMW R 18 owner seeking better airflow and reliable engine protection.