This all started in April, car has not been driven since.
I towed it to my mechanic (not too familiar with S2000s) and inspected the oil pan for rod bearing damages/wear. Found small amounts of very light/fine fragments in the pan.
Rod bearings were in good shape but was replaced anyhow since the pan was removed.

Valve adjustment was performed more than a year ago and did it again just to be sure its not it.
The car has a new InlinePro TCT that was put in last September.
Odd thing is from time to time on idle the ticking completely goes away. But once the engine is rev-ed, even the slightest, the ticking returns.

Could this be loose valves? Piston slap?
This is a 2006 AP2 with around 83,000 miles. Engine is all stock aside from the powder coated VC.
Here's what it sounds like:
https://www.youtube.com/watch?v=XEjdTLvuMCk&feature=youtu.be

 

I've had a similar sound before and it had happened when I had performed a valve adjustment on my own car, and lost one of the valve adjustment lock nuts! This caused the valve lash to be incredibly loose. Definitely sounds like a loose valve adjustment.
When is the last time you had a valve adjustment (I ask just because you should do them more often than specified in the owner's manual for the 2006+ S2000s)?

Here is the smacking sound I encountered:

 

I redid the adjustment recently and checked all the nuts. They all seem to be tight. My noise is slightly higher pitch than yours.
I read this entire thread https://www.s2ki.com/forums/s2000-un...umped-1168823/
and it seems to me I might have a scored cylinder...

 

Well if you buy a borescope, post the results

 

Good luck! Those damn powder-coated valve covers...

My experience is outlined here: https://www.s2ki.com/forums/s2000-un...ssion-1159577/

 

What were the factory bearings replaced with?

 

The VC was powder-coated more than 2 years ago and I made sure to give it a thorough cleaning. I have tracked this car twice, maybe close to 200 miles in total.
I did a Blackstone oil analysis after the last track session, readings were fairly OK but found some shearing in the oil sample.

Replaced with brown OEM bearings. All the originals were brown.

 

Oil shear seems common in this engine. Slight decrease in viscosity.

-- Chuck

 

post the Blackstone, I would like to see "ok"

 

Here's mine. Hopefully we can compare this to "cool's." Shearing and slight viscosity drop is listed as harmless on my two tests.



-- Chuck