secondary wrap is how tight the spring is set, look at the numbers on the holes the place the end of the pring in, for example hole 1 on the sheave and hole 6 hole the helix would be 70 (1 plus 6 = 7)......hole 2 and hole 6 would be 80 (2 plus 6 = 8.) the higher the wrap the tighter the sring will be, the tighter the wrap the harder and slower it is to shift out but the better your throttle response will be (backshifting)....the lower the wrap the faster the sled will shift out as long as you have enough hp and enough weight in the primary, too high of wrap and the engine will overrev and the belt will slip, to start it would put it somewheres around 60, 70 or 80 and then you will have to fine tune from there, for radar runs you would run alot lower wrap because it yeilds in higher top end, for drag racing you want the best acceleration, for trail riding you want good acceleration but also good backshift