My son is ready to move up off his TTR 50. He turns 7 in one month and is a good rider he is jumping and all that stuff. We race Enduro and Harescrambles. I'm looking at KTM 50's on Craigslist and keep seeing Jr, Sr, SX, SXS, and SX Pro or just Pro. Can anyone tell me what years were what and when they started calling them what? LOL I "think" we need the Jr, but don't know what model of 2009 would be considered the Jr. Also is there a particular year that is best to buy? Someone told me at our race last weekend to get a 2009+ Bc of clutch???