I just purchased a 525EXC and experienced overheating the first two times out. Dropped it by the dealer last week and they told me it was due to the stock KTM jetting. That KTM uses very lean jetting to get by US EPA standards, which have a reputation of running very lean on fuel causing them to backfire (pop), and run really hot. My overheating happen just the same way...spewing out of the puke hose from the neck of the radiator. Just got the bike back from the shop, so I haven't ridden yet on the new jetting. Stay tuned...Good Luck!