Not sure if it's actually true but discussions about them would suggest that dirt bikes and street bikes with two strokes like the NSR don't have the same reliability. I see a lot of seized piston threads on dirt bike forums but not so much on forums where street 2 strokes predominate.
Is it the use of premix and the pursuit of crazy fuel/oil ratios that cause what appear to be an inordinate amount of lubrication-based failures on the dirty bikes?

I have ridden both a CRM250 and an NSR50 and each failed but it was jetting issues and stupidity on the NSR and overheating and stupidity on the CRM. Anybody else seeing a pattern? I retained the oil injectors on both and do not look foward to messing with premix if i don't have to.

I see dirt guys measuring rebuild cycles in hours. I ride my bike daily, maybe 45 minutes a trip twice a day and it's going strong. I would be doing a top end rebuild once a week at that level of frequency.

Is it the oil injection and proper maintenance that is keeping it alive or are perhaps motors destined for street bikes a little less ragged edge in the way they are designed and tuned from the manufacturer?