Check out what this guy did he had the same problem (but mainly check this)
4) i purshased the 48p 96 tooth spur gear and a 15 tooth 48p pinion gear from HPI and it was a bad idea. with the high power 7700kv brushless motor i have, the carbon fiber spur gear got destroyed in 15 min. i adapt a
KIMBROUGH 32P SPUR 64T and a 15 T 32p pinion instead for durabilty. you only need to drill 2x 3mm holes in the plastic to fit it onto the hpi original spur holder.
Heres the full article
http://mczouav.blogspot.com/search?q=wheely+king