The RS250 is a VERY good bike. And although I'm the Director of the Aprilia USA Owner's Club (http://www.aprilia-usa.com
), I have owned enough bikes from Japan and Italy that I don't think I'm overly biased. These bikes ARE that good. I have nearly 10,000 km on my 1996 european silver Biaggi model and it has NEVER given me grief. Yes, they require a bit more tuning to stay in top shape, but these little bikes reward you with the best cornering of any bike I've ever ridden.
The top end rebuilds you hear about are on the racing bikes that are flogged hard every mile of every day. So a WSMC or FUSA racer running these will probably see a rebuild every 800-1000 miles. But again, tuning can make a difference.
First...a caveat...I'm the LEAST mechanical person you will ever meet. Computers...no problem. But give me a wrench and I'm a danger to society.
I have my RS250 tuned by Steve Biganski, who has probably the best reputation among 2-stroke engine tuners in the USA. I think you're in Phoenix right? I would talk to the guys at Cycle Moto in Mesa. They have a good reputation with us at the Aprilia USA Owner's Club. The Aprilia dealer list is at: http://www.apriliausa.com/ridezone/i...ers/ridefr.htm
What we have found the BEST place in the USA to be is Mototek Imports in Texas. (512-218-4466 Jay Bernard, http://www.mototek.com
). There is literally nothing they cannot get, including parts from Europe for my bike since it doesn't share certain parts with the cup bikes. Not that there aren't other good dealers...just that Jay has always come through for club members and has an impeccable reputation. They have a lot of troubleshooting experience too, being the largest Aprilia racing team in the country.
The important thing, from what I have been told and seen in action, is HOW your bike is tuned. You can have your RS250 tuned so that it is a full race bike and is running at the ragged edge to get that last horsepower, or tuned for a more moderate street/track level where it's more liveable day to day but still does well.
Mine has the Arrow full system, Biganski-worked top end, and modified intake/airbox. I'd guess I'm at around 63-64 rwhp up from 56 stock, but it runs very smooth and is very reliable.
BTW...Mototek makes a 316cc big bore kit that will see something like 75-80 hp if you're dying for more power and don't mind spending some serious cash.
Hope this info helps. Let me know if I can offer further assistance!