hello i have an 01 scrambler 500 2x4 that im pretty sure has the worn camshaft. idles great but at about a quarter throttle spits fuel back out through the carb. the question i have is when i pull the plug it looks really light brown like its lean? if the exhaust valve wasn't opening wouldn't the plug be black like it was rich?? im pulling the camshaft today to make sure the cam is the problem. ive tried two carbs. one brand new and the bike has the identacle issue with both. valves are set at .006 on both exhaust and intake and timing is perfect. thanks for any advice.