rotating the crank two wimes to check the marks just makes sure you used tdc of the compression stroke. the first time around your marks wont line up the second time they should. crank at 0 and the hole in the cam gear spoke should have the uppermost notch on the cam gear housing centered in it.uppermost reffering to the mark that is at the highest point in the cams rotation,not 12 oclock.(since the motor sits on an angle not perpendicular to the ground.