This is straight from the Husqvarna 1982 racing handbook for 1982 CR250, (handy little thing it is too).
Type: Mikuni
Vebturi: 38
Main jet: 410
Needle jet: R-4
Idling jet: 45
Needle position: #4
Air jet: 2.0
Throttle: 2.0
Needle: 6DH20
Air screw opening: 1.5 from bottom position
Cheers,
K