The same can be said of an air-cooled engine. As you may know, Club 100 run TKM BT82's for 50 plus hours before rebuild.
Without using pre-heaters how do you suggest warming the engine up? You don't advocate running the engine on the stand, no properly setup racing two stroke likes to idle for a lengthy period and, with one rolling lap, you don't have much choice but to hit high revs immediately. I'd say the Nikasil bore and lower revs were a greater factor than water-cooling for the longevity of the engine. The water-cooling and float carb gave less chance of user induced failure.
If failures have been shown to happen at 25 hours (or 10 hours or 5 hours etc) you have to weigh up the cost of failure against the cost of more frequent maintenance. For some, the cost of failure will be the cost of rebuild or at worst, the cost of a new engine. For those who value race wins, the cost may be the cost of the rebuild plus the cost of the wasted meeting. For those that value championships, the cost may be the cost of the rebuild plus the cost of the full seasons racing, ruined by one engine failure at one meeting.
The weak link in almost any engine is the bearings. When the bearing manufacturers themselves can suffer at the hands of counterfeit bearings, it's almost certain that a high proportion of Rotax engines have counterfeit bearings in them. Moreover, bearings don't simply "continue to wear until it won't run at all". As they wear, the rate of wear increases until they fail entirely. Without being able to break the seal, the user has little opportunity to check the bearings for signs of wear and replace.
Of course, Rotax could always remove the mandatory seal and only apply the warranty to those with seal intact.
Dave
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