Was facing heating issues with motor/esc/tail servo for the last few weeks. 
Config
HK 450 PRO
SuperBrain 40A | Hk 2223 3500Kv | 14T
Quark | JR 3500G

ESC Settings : Low timing | 8 PWM | Governor @ 3000 RPM

Gear mesh was good and no bindings on Tail

But still at the end of 5 mins - the motor was very hot (can't touch more than 5 sec, especially the top area)
Similarly the tail servo was also very hot.
ESC also felt hot, but couldn't touch it since it was under the battery tray
Surprisingly, the battery was never hot (40C zippys)   

Tried 13T @ 2800 RPM, but no improvement.
--

Finally, decide to replace motor with Turnigy 2218 3450Kv.
Today morning did a 5 mins test with 13T at 2600RPM.
Unbelieveable - everything seemed okay. 
So something wrong with the motor that cause everything to heat up??
So far seems that way - will further test at higher RPMs and confirm the results.

I just hope my servo/ESC/battery are safe and have not been affected (performance wise). 

It doesn't look like a motor issue as in every step you reduced the RPM of the motor and it seems that 2600 RPM is a good one so try the same RPM with other motor and see if everything remains cool.

Also did you resolve the tail servo heatup issue by changing the motor?

Yes - thats the strange thing. After changing the motor, everything seems okay even the tail servo!

BTW when searching for a solution - I came across a thread on helifreak which mentions the same issue (he has very similar config as mine)
http://www.helifreak.com/showthread.php?t=186137

I will try 2800 RPM tomorrow on this new motor and confirm the results. BTW i loved the way the heli flew at 2600 RPM  - very smooth i wish a had shot a video