What do you have in the way of air exits?  You have to get an air *flow* over the esc and to some extent the timer.  It doesn't have to be huge, just constantly moving towards the exits.  But, for air to get out, it must also get in and the spinner is not enough for that.  Also, the exits need to have a suction effect so that the airspeed is drawing air in the front and pulling it out the rear.

Get an infrared temperature gun.  They are not very expensive.  If things get too hot, the damage is already done.  Measuring it after the fact only confirms that you need to replace it.  You are doing the right thing sneaking up on it.  How hot is too hot?  If you can't hold it, it is too hot.
There should be a high temperature cut off in the ESC but that may or may not be the high for the motor and timer.  I would worry most about the motor.  Not sure which ESC you are using.

Ken

I know it is somewhere, but I can't find it.  A Picture!  Can you post one of the top and bottom with and without hatches?  Who knows, someone may have crossed this bridge already and has the solution.

The ESC is a Castle Creation Talon35. I am well below the amp rating on this ESC and should be OK. The BadAss motors can take over 300F (from their website). The battery is a 120C rating way more then needed but is the right size, weight and capacity. I think I need to open up the bulkhead for the wing mount to allow full flow through the fuse. There is an outlet on the bottom but having the flow also through the fuse should keep the flow going better.

Best,   DennisT.

If you can open it up fairly quickly after a flight then get it open and rummage around in there, paying attention to how warm things feel.  Obviously the motor can stand to get very hot so you probably don't want to lay your finger on that without great care.  The batteries should feel barely warm to the touch, and the ESC should be well under the temperature where you can hold onto it comfortably.

(Note that I'm a industry trained analog circuit designer.  Part of the industry (not university) training is that the temperature where you say "ouch" and want to pull your finger away from a surface is about 50 degrees C -- and for a system operating in room-temperature air, 50 degrees C on the heat sink usually means that you'll be fine up 55 degrees C ambient.  So if your ESC has a bare heat sink, and you can touch it without wanting to pull away, then you're fine).

(Speaking of 300F -- that'll make your finger sizzle, but not get a shiny patch.  Just in case you didn't listen about the "be careful of the motor" part.)

If the various important bits of the system are visible from the air intakes or exhausts, consider getting a cheap IR point & shoot thermometer from Horror Fright Tools.  As soon as you land, measure the temperatures of the bits, and make sure they're within comfortable ranges.