Use the paper strip trick. Take some paper and cut a strip that is the width of the spur hear and with the CB and spur in place at a guestimated mesh, turn the spur and feed the paper in. Then, pinch the engine mount closer to the left of the savage such that the CB gear presses the paper all the way against the spur gear with only the paper in between the teeth. This is the proper mesh. Lock doen the engine mount and take out the paper strip. Turn the spur by hand; this is how the gear mesh should feel on a brand-new spur and CB. (A used spur and CB will feel differently from the tooth wear).