HMS launcher mod fail reason

Recently i modded a hms dual shooter for  mfb. For light beys eg Ray Unicorn,it is crazy fast. But for heavy beys(any synchrome) it's even slower than a ripcord launcher. 
Procedure to make the launcher: simply put the mfb prong onto hms launcher with a perfect fitting screw
Can anyone tell me why cuz this problem? :chief2002hm:
https://worldbeyblade.org/attachment.php?aid=1238
my launcher is similar to this
well it is a modded launcher and hms is a lot lighter than syncrome. Syncrome is past that launchers weight limit,