hi guys ,i have a force .28 in my truggy and when i pull the trottle down quick it somtime does a sound like in this [link=http://www.youtube.com/watch?v=CdKc6Y70RMk&feature=fvw]video[/link] at o:39-0:42,0:43,0:58-1:03 thanks guys.oh and how to fix it too