I very much apriciate all of you guys taking time to answer. I belive I'm coming close to a final decision. Although an R80 engine would be a very nice solution, I think I will stick with its own R65 engine and work a little bit on it so it will get stronger. Dont forget its a 1990 model so all parts are interchangeble. According to Ulismotorrad mechanic to which I emailed the same question by changing the camsaft alone the engine gains about 10 hp. A pair of 32mm BING carbs can be purchased by a friend who is upgrading his R100 to the big bore kit and 40mm BING carbs, so things are on their way. Next step will be to find a pair of cylinderheads. I am not a speed freak after all even though the bike is a cafe racer I recently built ( didnt mention it before). Any more sugestions or talking about it will be taken under consideration though.
P.S. 1 any answers for message #24 ?
P.S. 2 how do I attach images?