The reason why is that you can build boost pressure on the starting line, with no load on the motor, by setting up the 2 step limiter with the right parameters. If turbocharged, and lowering the ignition retard RPM is not building any boost, a. 1982 Turbo Yamaha Seca 650 (Collecting Dust). (CLICK IMAGE to enlarge). /* 160 x 600 for right column */ For further information please call Dee Cranswick on (021) 465 3500. Enginebasics is the wiki or wikipedia of car part, repair, how to and tuning information. Throttle Overview.