What year is your 250r? My 86 will pull the front end off the ground in 1-4 if I let it. It's a stock machine so yours should be capable of similar performance. If you are new to 2-strokes you might just need to practice riding it some. I would also suggest checking your spark plug to make sure it's the right one and also check carb adjustments. You didn't say where you bought it from, but if it was from a different part of the country the altitude difference could require different adjustment or even new jets. Also if you are using the factory recommended 20:1 oil to gas ratio that could be helping it load up on you. Try 32:1.
If I can't fix it, it ain't broke!!