So the Chennai factory might have produced the odd set of "S" cams by accident, due to manufacturing inconsistencies. Excellent!
I suppose that is just about feasible as the Indian C.I. Bullet cams have broadly similar though not identical profiles.
Valve bounce on stock AVL cams aside, it has always puzzled me as to why a skilled engine tuner, with a good selection of performance cams known to work in classic Bullet engines, could only find one set of cams that would really do the business, and these turn out to be a set of touring cams. There's definitely something about the 500 AVL engine that doesn't seem to want to play by the rules.
I'm at a loss to understand why the head itself should be to blame, so is there perhaps some peculiarity in the rocker design that makes this engine so attuned to one particular cam profile?
Still puzzled.
A.