ok i was useing a 9.2 volt 700rpm and it is not fast engough by a countary mile! you need a 2000Rpm rotostarter, i am geting one and i will tell you about it when i get it...

and take a look at this i found it when i was looking around on you tube!

http://www.youtube.com/watch?v=X1kkwAr6tqE

that is the stock redcat brand rotostart! i guess it works pritty well!