Then it's too slow. LOL. But actually, motor temps don't seem to be affected much by gearing. On 4s I get the same temps geared for 50 (14 tooth) as for 40 (11/12 tooth), and 50 mph is much more fun. xD.
Check out my custom converted 8ight:
Sub 7lb, lowest CG of any 1/8 buggy