My yz250 gets a hanging idle but only when hot. Tore down and did a leak down test last night. It held 8.5lbs for well over an hour before I pulled the tester off. I understand it could be carburation but I'm trying to cross off electrical before I look at the carb. I should explain that before I get blasted... I switched to a Lectron but my Keihin occasionally had the same issue.