On my 2003 xr 650r I'm running a 165 main and a 68s pilot with the stock needle in the 3rd position, bike is fully uncorked with a white brothers E2 slip-on. The bike starts on the first couple kicks with no choke and a low adjustment on the idle screw, the fuel screw is at 2 turns out. But when I give it gas it boggs down and dark smoke comes from the exhaust. I have main jets from 165-175 and the problem has gotten better the lower I've gone. I still have the stock backfire screen in if that helps, any help would be appreciated.