In my defence it's been a long time singe they've been allowed to race motorcycles there. At least 20 years. And now you mention it I do recall bikes seizing at the end of pit straight, right down the bottom of the hill.
In your defense, anyone old enough to remember carbs how work, even if only slightly, is forgiven the occasional lapse of memory. ;-)
(And get off my lawn!)
If you find someone who _really_ knows how they work, pay them what they ask, and keep going back to them...
These carbs use an aneroid to move a needle valve at the base of the jet as the atmospheric pressure changes, effectively dynamically re-jetting the carb on the fly.
Got any keywords that'd lead me to something like that on Google quicker than me randomly searching? (Or even a link to such a carb?)
Edit: Found it. "High Altitude Compensator". Thanks anyway.
One of the old traditional racetracks here in Australia is Mt Panorama at Bathurst. It's got about a 180m elevation change between the start/finish/pit straight and the top of the mountain. Back when they were allowed to race motorcycles there, old 2 stroke racebikes were notorious for seizing at the top of the hill if they'd been jetted down at the bottom and hadn't been set "rich enough" to allow for the altitude change. Many many riders crashed and said "It was running really strong, til it locked up on me and spat me down the road..."
(No apologies at all for my off topic response to pedantry...)