Originally Posted by LukasM
2. Proven reliability: Absolutely critical. I can deal with issues that are known and can be changed out in advance (like base gasket NSU screws on the DR) but not a critical engine/gearbox failure without warning. Sorry to all you orange Kool-Aid drinkers, but that excludes the LC4. ....
I take it that means the Husaberg 650 motor is out. Too bad, that'd rip.
I was thinking of this the other day. The Xchallenge motor seems ideal, but the single exhaust outlet on the head may interfere with the frame downtube. Ditto the downdraft intake and the top tube.
A parallel twin would be great. A gs500 motor, or an ex500 motor like the Webers' Rallye Twin used. Good luck fitting the tank over either of them, though.
As far as reliability, the fussier motors might do better than usual in this setup because you have the extra oil reservoir and filter to add on.