Well, I am beginning to wish I HAD waited for a used CRF50. I greased, loctited, and tore everything down tonight. I completely disassembled the Kehin carb (#80 Main jet, and an UNMARKED pilot jet) and cleaned it, hoping to resolve the bog. NOPE, bog is worse than ever. I can't even rev it without almost killing it. I tried the clip in every position from stock (3 of 5 is stock), and no difference. This thing will not rev without feathering the throttle gently. It starts and idles super strong. It just won't run above idle. I have checked the plug and everything else. The air filter is stock, and un-oiled as it comes stock. I regret this purchase now.