Death Valley is a prime testing environment for an air filter | The 12,000-mile service on the new liquid cooled BMW R1200GS is a big one. It’s the maintenance milestone that requires a valve check/adjustment, spark plug replacement, engine and drive oil change, various system checks, and an air filter replacement. That final one is the focus of this piece.
I have used K&N oil filters for years because I trust the quality, and I appreciate the 17mm nut on the filter body for easy replacement. I have also used a full range of K&N air filters on my street-only performance motorcycles. However, the GS is an adventure (ADV) bike that I ride in a full spectrum of conditions over a variety of surfaces including dirt. I have been wary of using anything but the stock paper filters in the air-boxes of any of my adventure mounts (I have owned nearly a dozen ADV motorcycles of various brands). 
A side-by-side comparison of the filters emphasizes the K&N's build quality |
As is my modus operandi, I did careful research on the K&N air filters that are intended for dual-sport duty. I studied K&N’s filtration testing protocols and the resulting test data. I considered the ways K&N’s engineers added extra layers of tightly-woven cotton gauze filter media for the more demanding duty of adventure riding. I noted the filter body’s sealing bead and overall construction. In the end, I felt fully confident that K&N had developed a filter element that would add a higher level of airflow to the GS’s big cylinders, while still providing excellent filtration to protect the engine.
Comparing the K&N BM-1113 alongside the stock paper filter, the K&N’s build quality and well-designed sealing surface are notable. It has a more rigid body than the stock filter element, but the sealing surface is pliable making for a reassuring fit into the GS air box. The K&N filter fits perfectly into the air box’s support frame and seals up well when the lid’s four bolts are torqued into place. Of course, the final step in the easy and quick installation is the application of the K&N “do not discard” sticker on the air box cover.
The K&N is a perfect fit in the GS air box and the seal is secure |
So with the 12,000 mile service complete, including the installation of the K&N BM-1113, it was time for an adventure. The filter’s first ride would be a 1000-mile journey that would include an exploration of Death Valley, including miles of the region's dirt roads. Since Death Valley boasts the lowest point in the United States, the filter’s performance in low elevations would be tested. The ride would also include an extended high-speed freeway leg, and finally a twisty climb into 9000 foot elevation of Arizona’s San Francisco Peaks. That is clearly a viable real-world test of a filter’s performance.
So how did the filter perform? On the road, my seat-of-the-pants conclusion was that the filter’s airflow smoothed out the bike’s annoying hesitation when accelerating from about 4000 RPM. The roll-on performance was smoother and stronger. Yes, I know it is only seat-of-the-pants testing, but I will tell you that my seat spends countless hours and miles in the saddle, so I get to know my bike very well. I will vouch for the noticeable improvement in mid-range performance on the GS.
ADV bikes have multi-surface capability which requires effective filtration |
As far as my overall performance impressions, they too are very favorable. The ride included an elevation change of over 9000 feet. The bike performed flawlessly at the negative 282 foot elevation of Death Valley and the heights of the northern Arizona mountains. An especially notable performance boost was the crispness of the bike’s throttle response at the highest elevations. Clearly the added airflow helped in the thin mountain air.
Upon returning home, I removed the K&N from the air box for a post ride inspection. The filter’s seal was secure and the element looked perfect. Of course the air box was spotless. I have no reservations about running the K&N BM-1113 for the next 100,000 miles that I expect to keep the big GS. I am also more than pleased that I can wash and re-oil the filter after a particularly dirty ride, rather that trash a paper filter. This adventure rider is now a convert.
For all K&N air filters for BMW R1200GS models, visit the BMW R1200GS Air Filters page.
The re-usability of the K&N filter is a big bonus for adventure riders |
The filter performed well through extreme elevation changes |
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