Micro Rally BB2 question

[AntxmodMiniz12322]

wow i havent been on these forums in months, but i came to ask a question about my losi micro rally. I have a bb2 motor in it and it works just fine but when i use a lipo battery it slows down alot. i know its not the battery because i use it in a Mirco sct with the stock motor. i just wanted to see if anyone knew if the bb2 is meant to have the 4 volt battery and isnt mean to work with 7.4 volts of is my motor screwed up?

thanks
ant