Place the stem bolts in the stem while the crossbar is still resting on the frame and twist them in a few turns with your hand. Move your bars to where you prefer them to be positioned. Tighten the stem bolts with your allen key a few turns at a time in a star pattern until the bars are secure. Do not use a lever, the grease on the bolt threads allow sufficient tightening of the stem bolts with an average amount of force.