Has anyone thought of using a Triumph 675 street triple engine in a 690 chassis. Before I get lynched the power is excellent and the torque figures are excellent. With a bit of re-tuning, different cams and power curve etc the 105 bhp could be reduced and the torque bumped up from 68Nm. 68Nm is already not bad for a relatively small displacement motor. I can't find the actual weight of the engine but the whole bike only weighs in at 182kgs and the engine has won many awards and has been around since 2008 so a lot of the bugs have been ironed out. The street triple is a very compact bike and goes like stink. I had one for the day when my 1190R was being serviced and the engine is a peach.
Just a thought from out of left field and I'm waiting for the backlash