I cleaned the rotors that I intend to use, soaking them in carb cleaner
for
 a week.  They clean up real nice.  I noticed a patchy light almost looks
 like an adhesive deposit on the side surface located between the side
seals
 and the edges of the rotor.  Does anyone know what this is? Thanks

 Joe Berki

 It is probably a Teflon coating that reduces the crevasses around the edge
of the rotors
 to reduce unburned HC storage for emissions reasons.

 Paul Lamar

Paul,

I can feel the pitting with my fingernail.  It could be corrosives in the
fuel or oil.  It is on the combusion side.  I will try to get pics.  Also
found a small ding in the rotor face that is far away from the apex slot
and
bathtub.

Joe Berki

Joe/Paul,

I've recently cleaned up two sets of 20b rotors and both had a light-colored
material on the face of the rotor from apex to apex, but nothing on the
sides.  Most of it was worn off, but you could tell that it had been coated
with something.  My guess is that it is a ceramic thermal barrier.

Mark S.

Somebody should try chrome plating on the rotors. In theory that would reflect radiant heat from combustion, reduce the oil temperature  and improve the BSFC. Chrome plating works well on the steel rotor housing liner.

Paul Lamar