CR125 1992-99 Phathead Flat Top Kit HF12592 This Phathead Flat Top kit fits Honda CR125 1992-99. Phathead Racing’s Flat Top kits include a Wiseco GP series 762 racers choice flat top piston kit and a Phathead set with domes designed to be used with these high performance flat top pistons. This kit will increase low to mid range power and resist detonation. If you are using fuel around 90 octane use the H12. If you run fuel around 100 octane the H13 works well. If you run race fuel with 105+ octane the H14 dome with this piston will produce an impressive amount of power. The standard two domes for this set are the H12 (7.6cc) the dome closest to stock, and one step higher compression H13 (6.7cc). The higher compression domes available are the H14 (5.8cc) and H15 (5.0cc) domes. When selecting domes, the smaller the cc the higher the compression. To order a flat top kit, choose the color of head body with the drop down menu below. Enter the 2 dome sizes you want with the set. By entering no dome selection defaults to the standard set of domes. WARNING. When using the higher compression domes you must run high octane fuel. Running low octane fuel in a high compression engine could cause serious engine damage.