This engine suffered a loose bolt in the head and starved a camshaft of oil. The cams and cam caps are toast.
I then purchased the engine from the seller quite cheaply. One of the bores has a mottled color to it as pictured. To the touch the surface feels like a mirror and with eyes closed it would be impossible to detect any difference of the surfaces. Has anybody came across this before?
The remainder of bores appear normal.

 

Never seen that before, no. A light hone which should be done anyway before fitting the new pistons/rings should clean that up.

 

 

Aluminum oxide, 00 steel wool, or a 600+ grit silicon carbide dingle hone should get that out. You only need to rigid hone the block if there are scratches that catch your finger. If the bores are visually in good shape, honing is completely unnecessary. FRM will outlast the rings under normal circumstances. The material is porus so crosshatching makes no difference to the materials oil retention properties.

If you want to hone anyway, the only thing that will make a difference is the exposure step, especially in your case.

 

The MMC layer in this engine does not contain silicon; no etching treatment step is necessary as in an A390 hyper-eutectic block for example.

 

Sorry I forgot to reply to the OP. Hard to speculate, but if the block has been hot tanked in a chemical solution that's not compatible with aluminum, or some sort of chemical reaction took place in that bore due to sitting etc, etc, then the MMC layer may be compromised to the point of not being usable.

 

The substrate material doesn't react with oxygen, only the aluminum, FRM is not iron. Are you assuming the sleeve is compromised from some aluminum oxide? Really?

 

Not sure why you would say that, our sleeves are hypereutectic. The cylinder sleeve is aluminum with FRM embedded, you still need to do the exposure step. Otherwise the rings are going to ride on the aluminum.

 

Refer to SAE Paper 890557 for details. One of the reasons Honda chose the FRM was to avoid the expense and complications associated with Si and the exposure steps. The FRM is 9% carbon fiber and aluminum oxide; there is no silicone.

 

Thought it was about weight saving and longevity ,or may be a lot of slurry & gas involved S&M
http://rdo.psu.ac.th/sjstweb/journal...-2-215-220.pdf