Fast Rustler XL-5

I recently put some proline dirtworks on rpm rims on my rustler xl-5 and as soon I started running it, the motor burned out. I put a new motor in and with a fully charged 8.4v 3000mah nimh it was fast, much faster than I have ever seen it before even though I went up 4 teeth in my spur gear. Is this bad? the motor was 107 degrees farenheit but not a very accurate thermometer.

call me ignorant but i never watch my temps, if you wanna go faster go with less teeth on your spur and more teeth on your pinion, overheat protection and lipo made me lazy.