[The_AirHawk]

Note the convex "scoop" on the side of it for cooling (you mentioned this problem in an earlier post). Also note, the bike to which it's affixed appears to be an aircooled single, probably making sub-30hp, even in vintage race-tune. Not so much heat to dissipate as a more modern engine of the same displacement, but more power.

The more smoothly you make the air flow-around the bike, the harder it will be to make it flow through your cooling means. I've read before that this was a major problem that plagued virtually all the dustbin bikes, and was never satisfactorily solved before their demise.

It was a compromise of the first order: the bikes could be made to go much faster, but would overheat immediately. Divert enough air to cool the bike, you lose-out on the full potential, maybe cost yourself a race (and a championship). And what was "optimum" could change day to day, or even throughout a given race.

Sum-total of my knowlege of the Dustbin bikes, right there. And it's been probably a decade since I read anything on them, so some bits may be mis-remembered. But the gist of what I read (that caught my interest enough to remember) is there.

 

[The_AirHawk]

Your forgetting air cooled bikes take a lot more air flow to cool properly though. They weren't all air cooled then. Take the MotoGuzzi V8, no over heating problems with it and it had quite a small scoop (I've seen it in person, so pretty)

My 125 even in 110 degree willow springs summers takes very little cooling, often I have to tape half of the little radiator off just to keep it warm enough.

You can also arrainge the flow of air so it goes through a radiator then back out cleanly which helps some. In the bike my friend put a dust bin on though he just left the large opening where the front wheel comes out and that's been enough to keep it cool. Of course he's far from racing it.

Nah, I'm not forgettin' all that. I've seen lots of non-stock "strategic ducting" on various bikes. If you direct it, the cooling air is more effective than just "ambient radiation" of the heat. Have you ever been through the Barber Museum? If not, you OWE it to yourself to take the tour, look over some of that vintage iron closely. It's amazing (to me) some of the clever ways they came-up with to solve problems (like overheating, as just one example) back in the early days of racing - things that are a non-issue today (either due to better metallurgy, plastics, manufacturing practices, etc.)

When I was younger, I used to think that racers and engineers back then were somehow "dumber" than today. As I've learned since maturing a bit; not even close. Makes one think: how will they view racers of TODAY in another 60-80 years?

 

[The_AirHawk]

Hell, you could get a Harley Ultra Classic up to 250 mph pretty easy if you dropped it out of a B-52 at 40,000 feet. Chances are that's not much use in the real world either.

Mebbe not - but it might make for a good YouTube Video!