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My 2007 crf50 ran great until this past weekend when son took a couple spills while riding trails. It instantly was hard to start and runs terrible. I have tried everything i can think of. I have a 2004 that i swapped cdi box, spark plug wire, entire carb and same result. Tore the carb down and appears great. So here is where im at now. The bike will start and run great while standing straight up...as soon as i lean it either direction it will sputter out and die! Im lost!

There was no damage to the kill switch wiring, so the movement either way earths it out causing it to faulter?
I would look at the carby breather hoses aren't kinked or filled with dirt. Perhaps worth check float level and if a baffle is installed, it is still in right place.