You may also get a better response if you post this question in the revo forum.

Welcome aboard, quick revo! Tell me a little more about this noise. is it coming from the starter or the motor? My guess is that it is the motor trying to fire, but the glow plug may not be hot enough (new motor draw a bit of power during starting and reduces the power sent to the glow plug). Try using a seperate glow igniter for better results.