Your certainly headed in the right direction. I bet either would work, I went with a 41, but I still want to try a 39 as well just to see the diff, dyno curves, etc. My guess is the 660 Rallye gets by with a 39 as IMHO its motor is a better matched to this with the high compression, they really need the low end, dual exhausts, and that garage the rallye calls an airbox, etc. I suspect a FCR41 fitted with a Powernow intake will operate much like a 39, that is my plan. Still a properly priced and well sorted 39 might just be the ticket. Cheers, Mack
PS. I would think that it might make a difference if it is a pre-03 or otherwise.
Österreichische Motorräder und deutsche Autos. Wie wundervoll kann das Leben sein