Gearing ? with temps in mind.
 

My bl mbx 5 buggy uses a 7XL with a MM with a fan on 14 cells, & the gearing is 13t pinion & 46t spur. The temp on the MM is a round 140 & the motor is 116 at the heat sink & 160 at the rear endbell after 10 minutes under race conditions. Does this sound good or should i change my pinion ?.

If you like to cool the esc a touch you could try a 12. I would keep eye on motor as well.

Sounds good to me! As long as the temps are below 180, it's fine IMO. Do you like the performance you're getting?

Could my 7XL be under geared or over geared by using a 13t on a 46t spur with the temps i described in my first post or would you be satisfied ?. The speed is great but i might like a little more runtime.

Well if esc is hot the motor is over geared.
If motor is hot it could be either accually.
If you want a little more runtime try a smaller pinion.

The ESC is around 140 when i read the temps from the side of the heat sink.

140 is no prob. The temps are good accually.
Just not sure if you want cooler or not.