I recently purchased a 2003 xr70 for $250, I know a steal...even if it needs a top end...When I purchased it, The carbs air needle was stripped and I couldnt tap/die it out so I sprung and went for a brand new OEM xr70 carb. After installing it I was just test riding and any time I go from 1st to 2nd gear it just completely loses all power, I cant even make a swooping turn with a slight uphill grade without it going out. I can't seem to pinpoint the issue. I shrunk the front sprocket from 15 to 13 teeth from another post I've read and it did seem to help. But anytime I've ridden a stock 50/70 in the past I could start out in 2nd gear. not the case here, it just bogs out. This bike is bone stock. If your're telling me there might be a piston and rings in my near future it won't hurt my feelings because I'll go to the big bore 88. Oh, checked the valve clearances and the timing. Valves were good, Timing was forward one tooth, so I thought that was the problem, not the case. The bike looks like it has been beat on pretty good but most mini's are. HELP! P.S. this is my first 4 stroke dirtbike, I normally roll on an 01 cr250.