You may be riding in technical stuff way above my pay grade, so maybe you need the low gearing. I have the 15, 2 of them in fact. I also have the 17 tooth. I am back to running stock.
I can do that because I addressed the very lean fueling on the bike at low rpm. I did it after looking at the air fuel ratio on a 800 on a dyno. 17 to 1 at idle. It does not make a decent ratio until it spools up passed 2,200rpm.
Trying to trail ride the bike at low rpm, due to the high gearing, is almost impossible, because it makes no power down low. The jerky throttle is caused by going from super lean fueling to adequate in the course of about 1,000 rpm.
Power commanders, accelerator modules, Booster plugs and High Tech Coon Ass module are all solutions to one degree or other.
If you address the low rpm fueling on the bike you can actually lug the motor. I can accelerate from 1800rpm in 6th gear. In the bottom 4 at 2,000rpm, I can accelerate briskly away to various degrees. At idle, using the brake, I can bring it down to 800rpm without stalling. None of that is a good idea, but gives you an idea of the improvement.
May not be good enough for you, but a definite improvement and certainly makes the bike easier to ride.
As for the mileage, you are right, the faster you go, the more gas you burn. I get 56mpg at 65 and around 45 at 75. My only advice is slow down.
BMW Motorrad USA customer service: "We make superior motorcycles and continue to improve them."
itsatdm screwed with this post 05-14-2012 at 12:12 AM