Bm fuel consumption and Bodge up
 

Does anybody have a link to fuel consumption on flat twin Bm's or can tell me the average fuel consumption on air and oilhead Bm's, one other i know it might seem a strange ask but can the neads from a 800 be fitted to a 1000. Also have a plan to convert a r100rt in to perhaps a more dual purpose machine. Get rid of the ginormous fairing. Then when the need arises change the footrests and handlebars to suite different applications, mayby even have a spare set of wheels. Only using the rt as i have an offer of one with low miles any idea's pics thanks Floyd

This should anwer your questions re mileage etc.

BMW Motorcycle Models

The Airheads are not particularly fuel efficent, lots of volume in the dated combustion chamber design.
My low compression '92 R100GS averages 37 to 39 M.P.G. in my mixed driving commute, but can do as well as 44 M.P.G. out on the road.
I don't believe the 800 head will work on the 1000.
Seems a shame to take off the RT fairing, it was one of the best ever made.
The best place to learn about Airheads is the "Old School" section at advriders.com.