hi i have a bigbear 400 that had a carb that was floading so i replaced the needle and seat . new float and diaframe i cleaned all the jets and the carb out but it want idle unless chock is half on tried adjusting air mixtue .checked for intake leaks .front exhaust pipe gets red hot.spark plug is white on the tipe .back fires through exhaust when coming down of high rpm back fires throgh intake can anyone help please.talk bowl of carb and the bowl was 3 quaters full of fuel .i havent checked valves yet because seems to be lean to me .i no it has some compresson because it nilly brakes your hand to try and pull start .tried blowing every hole out in carb used a thin bit of wire to clean out holes. new spark plug can anyone help please because i fill like just buying a new carb

 

If you are 100% the carb is clean and all jets are clean and no air leaks I would try to set all adjustments on the carb back to factory settings. It sounds like you have tried many different things and the carb could be out of adjustment. Not sure where to find how to set back to factory settings tho (maybe the service manual). That would be where i'd start. If it still gives you trouble it is something else(again only if you feel 100% you put the carb back together correctly).

 

those carbs are junk. replace the thing with a good one if you can get one from edlebrock or holley.