I dont often post material from MotoGP, I leave that to my colleague Neil Spalding (@Spalders). However every year Yamaha kindly provide a technical review of their bike. With this year being the last of the 800cc regulations, the analysis is that bit more poignant. The Press pack which I received is presented at by Kouichi Tsuji the YZR-M1 Project Leader at last race of the year. So while I lack the background that Tsuji-san provided in Valencia, there are some interesting sections related to aero in the slide pack.
Reduction in Drag (Cda) from the graph we can see the fairing from 2007 (shown left) was developed to greatly reduce the drag for the 2009 fairing. The new format being slightly slimmer in the middle section (now showing the exhaust) and more bulbous around the top fairing. The subsequent 2011 fairing then was slimmed around the area above the handlebars. These changes reaping a 12% reduction in drag. Along with increase in engine power top speeds would have been boosted by these changes. Critical in chasing the Ducati with its high top speed.
Aside from the exposed exhaust, the only mechanical parts sitting out in the airflow are the clutch and brake levers. These being slab sided CNC machined alloy parts. It was reported that the team found the aero drag on the levers at top speed was enough to push the levers back and to induce some braking pressure. So they machined out a hole in the outer face of the levers, to ease the drag created at the lever tip.