Well that's part of why i'm asking - even if P&G sucks is it still worth doing?
I'll state a bit more to see if it helps clarify. Most of all I would LOVE to have SFC figures for modern bikes. For instance on cars it's pretty much a given that they'll be the most efficient fuel use, per HP used, maybe around 2000rpm or so. At 1000rpm it will suck. At 5000rpm it will suck. But bikes have such an incredibly wide range, like the Ninja 250 with what, 13,000rpm redline?? I don't know where the ideal part of the curve is for such an engine. I would like to have something with enough power and gear, to put it in that sweet spot of the curve for 55-75mph range approximately. If a 500 is more efficient putting out a 15-20hp load than a 250 is (being run too hard) the 500 will probably get better mileage under those conditions - this i've finally understood.
I'm strongly considering aeromodding a bike (more willing to do with an uglier, cheaper, older rattier bike than something new and slick like a Ninja) but my fab skills currently suck so I don't want that to be a first or immediate project, it might wait a year before I do it, and i'm hoping the MPG of the bike will pay for itself before then.
Not looking at any kind of 600cc super sport - when I say 650 I mean the big singles and twins mostly, torquier stuff.
I'm becoming more convinced that I need more displacement - the guy with the 180mpg 90cc ultraslicked scooter is cool, but i dont want to see it on a mild hill and I know for a fact i'll be moving stuff by utility trailer, so the usability requirements are pushing me away from the smallest displacements afterall after struggling to find a way to make it work. Anything from 20-60hp potentially, just wanting at least 20hp to get around with some authority without overstressing things. A 250cc may still be okay though.