I've ridden in hot ass weather at high RPM's. I rode my MK80 60 miles round trip (PLUS the actual ride) to Kansas City almost every weekend last summer. If you set your bike up right you won't have problems. For any given tuning state you will probably experience more heat fade than you would on a cooler day, all other things being equal. You can correct this through various piston modifications, running a little more rich on oil (and rejetting appropriately), pulling timing back, etc. Or just don't go WOT forever. You've got the advantage of having a fan, so you will have more cooling air at all speeds than you would for a ambient-air cooled engine. I've got a Zuma (variated, fan cooled, high-rpm) that runs exactly the same - hot day or cold day. It's all in the setup; I'd say you're more likely to seize due to being inexperienced at tuning (I don't mean that to be derogatory) or any other number of problems than you would just because it's hot out.
