Join Date: Aug 2006
Location: Chicago, IL, USA
Many of us have opened the left side of the airbox on the k12r to accept two filters. best way to do this is removing the airbox and using a rotary cutting tool or hot knife. if you can remove the airbox, the cutting is easy.
then, i bought the stock snorkel for a s bike and cut it down to fit under the plastic. unfortunately, if i recall, the zfe computer is there as well and may need a little relocation. or not, i can't remember. however, it's completely doable.
as far as air flow, imo, the airbox is better balanced with two filter and it should have been this way from the factory (it is on the k12s and k13 bikes). The slight top end power deficet between the k12s and the k12r might have to do with this slightly decreased flow. (although IMO it's the VERY narrow size of the snorkel that is the limiting factor. Many people remove this as well)
either way, IMO and in my experience datalogging a/f ratios(I've got the pics of screen shots somewhere here), the stock computer is already too rich at the top end and the improved airflow is only going to improve that. In other words, no need to remap. and if you do, you want still less fuel on the top end...
Many people have this inaccurate idea of a/f levels. yes, there is a point where the engine will make best torque, but a motor will run on a HUGE range of a/f levels. And there is no magic a/f number. different engines will like different numbers even at different rpm ranges. Take a look at the stock BMW fuel map. at one time, there is a lean hole with a/f ratios 15:1 and more. Somehow that was accceptable to BMW. My point is that an exhuast change, a filter change, other "minor" changes like that will NOT likely need remapping unless the stock map is way off to begin with.
'06 K1200R- in pieces
'73 Honda CB500F- slow but fun.
'77 Yamaha XS 750 triple- kinda
Last edited by JCW; Mar 15th, 2013 at 12:06 pm.