It's not so much that the engines suck, it's that you're cranking 150+ hp out of a motor (bone stock from the factory) that weighs less than 100 lbs, and is run at nearly WFO nearly 95% of the time, it's an incredibly harsh environment/treatment for a motor, and the fact that they can not only do it but hold up like they do is really impressive. Then throw a turbo in the mix and you're talking a solid 250 hp

All from a machine that weighs in at or below 500 lbs ready to ride. It's an impressive feat of engineering when you really look at it. However, there's trade offs involved there, powerplant lifespan is one of the biggest. Cost/extreme depreciation is the next one. When I bought my first brand new sled in 1999 it was $4800 out the door and while it wasn't the biggest and best, it wasn't the bottom of the barrel either. The last sled I bought brand new was in 2012 and it cost me $12,500. I sold it last weekend with less than 1800 miles on it, and over $4000 worth of repairs and upgrades over the 4 seasons I rode it for $7000 and I got a GREAT price for it since the guy who bought it knew me and knew he was getting a hell of a good sled for his money. So in 4 years I got less than 50% ROI on that thing and 1700 ish miles of enjoyment. That's a lot of cash per mile, and it's not including Fuel, Oil, transport, gear, etc.

If you want a better motor life, buy a Yamaha 4 stroke, but you're going to pay a 100-175lb weight penealty on that machine too and in the mountains, that's not a good deal because you ARE going to get stuck, and every pound is one you have to dig out. Not to mention the HUGE difference in riding a heavy machine, let alone riding it well, in the trees, etc.

This is why the 2 questions I posed to the OP are probably the most significant part of the equation, uses and budget, and I should add expectations.