14-18 YAMAHA YZ250F: Motion Pro Revolver 2 Throttle Kit (Standard) The Rev2&trade; throttle has several different size reels that will change how much twist is necessary for the throttle to completely open the carbs or throttle bodies on a motorcycle. The larger the reel is, the shorter the twist. Each reel size will shorten the twist by about 10 degrees. If your stock throttle has a 40 mm reel and stock twist is 90 degrees (1/4 turn), the 45 mm reel will reduce the twist to 80 degrees and the 50 mm reel will reduce it to 70 degrees. The 35 mm reel will increase the throttle twist to approximately 100 degrees.