1968 Evinrude Big Twin, Big Twin Electric, Lark 40 HP Outboards Service Manual, Page 27Get this manual
NOTE DO NOT attempt to check the operation of automatic choke unless the motor has cooled to room temperature (700)Operation of the choke during starting and warming-up cycles cannot tested accurately warm motorUsually motor temperature wiH normalized sufficiently if the motor has allowed to stand for period of hour with the cover or two hours with the cover
Figure 3-19Throttle
Adjustment
Loosen center screwDO NOT disturb position of needlePosition knob so that it is pointing straight and push back to original position needle, leaving enough clearance so that knob will turn without bindingTighten center screw to secure knobfAdjust idle adjustment screw so motor will idle at 650 rpm IN GEAR
Figure 3- 21Adjusting Automatic Choke