How often do you replace your air filter?

[MThomas]

and do you use the disposables or the K&N wash 'n re-use?

[towerworker]

I think BMW recommends every 30-36K, more often if you ride in dusty conditions. Never used a K&N. I once was advised to stay away from the K&N based on the thought that they didn't filter down as fine as the BMW. I don't know if that's true.

[gregor]

Probably twice in the 10 years I've owned the bike , using disposables. The debris has been noticeable both times- however there has been no change in performance after replacement. But I only have done around 2000 miles average per annum.

[AZBMWRIDER]

I replace mine about every 3 years, which is about 15,000 miles, with disposable type filters .

I live in a very dusty area, low desert of south central Aridzona , I remove the filter every year and blow out any debris and clean out the airbox .

I have stayed away from K&N type oiled cotton gauze type filters, not very effective in my environment .

[CycleRob]

I used 3 air filters in my R1150R's airbox in 64,000 miles. It was rare that I rode in a dirty environment. Removing the BMW paper filter every 12K mile service and gently tapping the air filter's rubber base parallel to the cement floor will jar loose a lot of captured grit. Do not hit it so hard that the pleated paper folds start to buckle away from being straight as they will be permanently damaged. Using a shop air blow gun is not recommended as it can permanently embed grit particles into the paper and damage the media paper.

Unlike carburettors, the fuel injected by EFI is not dramatically changed by a slightly dirty air filter. The ThrottlePositionSensor (TPS) determines the mixture at zero to full throttle and the O2 sensor trims the smaller throttle openings of that mixture by "reading" the exhaust CO2 level. Also playing along is the IntakeAirTemp (IAT) sensor, Oil Temp sensor and RPM data.

The K&N filters are real popular with the Go-Fast crowd because they do flow slightly more engine intake air that does provide slightly more power If/When the carburetted bikes/cars are properly re-jetted richer. Fuel injection bikes/cars are less susceptible to airflow induced mixture changes because modern EFI does not rely on the airflow to fully determine the fuel injected -but- the extra airflow will generate slightly more power. I do NOT recommend K&N filters for street or dirt bikes because they do pass fine silt particles that collect on the opening mouth of the Carb/TB as a thin brown paste. The reason why/how can be seen when a newly cleaned and oiled K&N is held up to the Sun (or bright light) shining thru the OD to the ID when you peek over the top. You will see many twinkles of light that will NOT be seen using the same test with a BMW paper filter.
Race Bikes need and get more power with K&Ns -choosing/knowing- it will NOT be a 20,000 mile engine. That bright light test (and seeing the K&N's brown silt paste deposits) made up my mind forever.

[MThomas]

I want to keep my bike a lot longer than 20k miles so I'll stay away from K&N but that makes me wonder, what about in the car? I currently have a K&N in my B6 A4 NA...

[peels]

have the paper one. I just shake it then gently blow it out with air gun every season. (they say this is bad, but It works for me-blow inside out first)

going on 3 yrs. Have new one on shelf. will replace when it looks tattered.

also check for mice in there occasionally, and I check filter then.