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Every 250 track will have slightly different characteristics, but the general conceptual line for a 250 has you doing 3 laps with the last lap being timed right in between turns 1 and 2 right to the line. I call the laps 3,2,1, because it's easier to remember this for me as th laps are counted down in the lead up to your run. You'll start your race on the apron on the back straight with 3.5 laps to go. Enter track and get some reasonable speed up to keep you upright. Hit turn 3 at the red line and cut a level line across through turn 4. Spend lap 3 working a shallow line to the top of the track throughout the whole lap. Conserve as much energy as possible doing this. Use the straights to move up, and cut a level line across the banks. When you start lap 2, you should be at the rail. This lap will be similar to riding the rail at a 333 before you jump. You'll start a seated acceleration coming down out of turn 2, and you'll jump out of the saddle in turn 3. Stay high in turn 4 and hug the rail as you come down the straight. At the pursuit line on the home straight you'll drift down the track towards a point on the red line in the middle of turn 2. This brings you into the Final lap, or Lap 1 as I like to call it. THe corkscrew your coach was talking about is this final approach. Picture a penny being dropped into a funnel. You'll hit the timing strip about midway across the sprinters lane, and you should be exiting turn 4 at the black line. Ride like hell to the finish.