Four Strokes Can't Match The Reliability of Two Strokes
I've had experience with both 2 strokes and 4 strokes. I had a 2001 yz125 for 5 years. I never changed the engine oil one time (I know that's terrible), and never even replaced a top end. And even if I had to we all know what that costs. A mere roll of pennies in comparison to its 250f counterpart.
My most recent dirt bike was a RM-Z450. I had that motorcycle for 3 months and had to replace the cylinder, piston, valves and all other top end parts. Everything I replaced cost me over $1100 (I live in Alberta, Canada).
Now to me the big companies want us to ride 4's because we pay x amount a year to maintain these "fragile" machines. When we buy a 2 stroke we literally only have to spend 10 bucks a month on chain lube and gas mix, the occasional spark plug, and for some the occasional $100 top end kit.
In my 20 years I've had a kx60 2 stroke, a cr80 2 stroke, a cr and yz 125 both 2 strokes, a yz 250 2 stroke and the earlier mentioned RMZ. Not one time have I done any engine work to a 2 stroke dirt bike under my care. And the one "high performance" 4 stroke needs a complete rebuild?
Now you could say that because I've never done any work whatsoever to the 2 strokes I've had that I'm a fairly careful/easy going rider and that's a fair and true assumption. I rode the RMZ with the same easygoing rides and I actually took way better "preventative" maintenance care of that bike with new oil every 5-10 hours. So how come it blew up? Because quite honestly with how light and high performance these 4 strokes are to compete with their half sized 2 stroke counterparts (how pathetic is that) they're way too finicky and fragile. And unless you can tear apart these machines and repair everything in a cheap manner yourself, then 2 strokes should be more available to the consumer because even the average guy can fix them himself.
Two strokes still go like snot and we all know if engineers for major companies put effort into these machines that they would be as good if not better than 4 strokes. But having said all that I still can't deny that I liked my 450 4 stroke. It was definitely a fun easy ride, but unreliability really turned me away from the machines all together. I think it's not fair to us, the consumer.