I would be interested in hearing your reservations about K&N filters. I am skeptical as well but would like to hear other views on the subject.
My K75 had one when I bought it. I gave it a through cleaning but I have also read the OEM filters are good for a good long while. Thinking of changing out to original.
This is my opinion only, there are lots of others on the web. I do not wish to create a pro-con thread on K&N, there are plenty out there.
The advantage of the K&N air filter is advertised as two-fold, never buy another and increased performance.
In addition to advice from others much more experienced than me such as Rob Fleischer (Snowbum
http://bmwmotorcycletech.info ), my work at a Chevy dealership taught me that replacing an OEM paper filter is false economy. While there were a number of instances where over-oiling the filter caused MAF problems there were also issues where the change in airflow caused a CEL which we would not diagnose without an OEM filter which frequently cleared the problem. Today's engines are engineered with many components, change the characteristic of one and you upset the balance. Our engines are not so complex and many others have opined that the OEM air filter is more than adequate for the job for an extended amount of time.
There are many who have used these for years with no discernible problem but I always question that the increased airflow=performance formula equals more dirt in my engine. Anecdotal info for me was from a friend who runs a beef farm and maintains all his vehicles along with sending oil samples away for analysis. The one engine he used a K&N had a significant increase in oil contamination causing him to return to the OEM paper filter.
As with many opinions you will have to decide which you choose to believe and follow, after all it's your motorcycle. For me, as with most non-OEM substitutes, is it worth a few dollars saved over the long run?
