I purchased a poorly running 90' CR 500. The seller told me it would not idle and wouldn't rev. past 5K or so. In an atempt to throw parts @ the problem the seller replaced the carb, coil, stator and rebuilt the top end. After the purchase I checked the basics- air filter, silencer and pipe for clogging, carb cleaned/ stock jets/ float height etc., reed- no cracks, good seal, timing marks aligned, new plug. The bike was a bear to start and w/ the choke on it reved like the throttle was wide open... I said must need crank seals. The bike fired right up w/ the new seals. Went for a test ride 1) turning the idle speed up doesn't increase the idle it will die w/ the throttle closed 2) It doesn't like any load or it falls on its face- choke on or off. Plug is really dark. So I try the original carb- same problem. What next? it seems really rich but the carb is bone stock. Reeds??? Any help would save this bike from a cliff. Thanx