K&N KA-4018 Reusable Motorcycle Air Filter

The K&N KA-4018 is a vehicle-specific motorcycle engine air filter with a trapezoidal shape. Its washable, reusable oiled-cotton design is intended to avoid routine replacement-filter purchases, but fitment should be confirmed for the exact motorcycle year and model.

At a glance

Washable and reusable design uses pre-oiled cotton gauze, according to the listing.
K&N says the filter is designed for high airflow and can help improve horsepower, acceleration and engine response.
Application-specific sealing features are described as supporting an OEM-style fit where applicable.

Price

$55.19Save 20%

Reference price: ~~$68.99~~

Price checked: Nov 14, 2026

View offer

Often bought together

Ngk LMAR9G Candles | Dependable nickel electrodes for cars, marine and small engines. Up to 30,000 mile typical life.

$16.29

Pros and cons

Pros

Reusable construction may reduce how often a replacement filter needs to be purchased.
The manufacturer describes a vehicle-specific design with application-specific seals for fit and installation.

Technical specifications

9 specifications

Identity
Brand	K&N
Model	KA-4018
Fit type	Vehicle Specific Fit
Product grade	Performance Part

Dimensions and installation
Form factor	Trapezoidal
Weight listed	0.37 kg

Construction and service
Filter media	premium oiled cotton gauze
Included component	Air Filter
Quantity	1

What to know before buying

Listing details to confirm

Fitment information is inconsistent: one highlight names select 2018–2026 Kawasaki EX400, Z400, Eliminator 500 SE and KLE500 models, while the product description lists numerous Ninja 650, Z650 and related EX650 applications with different year ranges. Confirm the exact motorcycle and year against the selected listing before ordering. The advertised performance and protection benefits are manufacturer claims, not independent measurements.

What’s in the box

Included

Air Filter

Who is it for?

A good fit for

Riders whose exact motorcycle application is confirmed and who want a washable, reusable replacement filter.
Owners looking for a vehicle-specific motorcycle filter rather than a universal filter.

Less suited to

Buyers who cannot confirm their exact motorcycle model and year against the listing.

K&N KA-4018 Reusable Motorcycle Air Filter · photo 2 — Additional product photo 2

Customer reviews on Amazon

4.4 / 5 · 145 ratings

5 stars75%75%
4 stars10%10%
3 stars6%6%
2 stars1%1%
1 star8%8%

Aggregate ratings lean positive, with most ratings in the highest star category, but a smaller share is in the lowest category. Without written feedback, these figures do not explain the reasons or establish fitment or performance outcomes. Confirm compatibility independently for the intended motorcycle.

Frequently asked questions

Is the K&N KA-4018 reusable?

The listing describes it as a pre-oiled, washable and reusable filter. Follow the manufacturer's service instructions for cleaning and maintenance.

Which motorcycles does it fit?

The listing gives conflicting application information, including select EX400 and Z400 models as well as several Ninja 650 and Z650 variants. Confirm the exact year and model before purchase.

Does it guarantee more horsepower or acceleration?

No guarantee is established. K&N says its airflow design can help improve horsepower, acceleration and engine response, but those are manufacturer claims rather than verified results.