99 bear back fire thru carb how do i set timeing or ck coil volts,is there way to adj. idol very low then bk fires thu carb and dies

 

Its most likely a carb issue. Backfire is a sign of lean. Posibly the intake valve is a bit tighter than it should be, and that wont let the intake valve close completely. Start by Checking the clearance on the valves, and clean the carb, especially the pilot jet.
There should be a screw, on the carb,near the thottle cable, for adjusting the idle.