I used to race karts when i was younger and am wanting to get into mini sprints, i however have never heard the distinction between d1 and d2. i know that the 600's run an offset engine and 1000's are contained inside the cowl, and sprints run a wing and midgets don't but what does d1 and d2 mean? Sorry I am just trying to get into it and familiarize myself with the terms.