86 I rotor thickness question

[JohnF]

My 86 Interstate has 5mm rotors on it. I bought pads for a 5mm rotor setup but the left front caliper (hand brake side) pistons are WAY open when the pads engage. Almost like this caliper is for the 10mm rotors. An I missing something? Normally calipers I've replaced pads on have to have the pistons shoved back inside as far as they will go to get new pads in. As I recall the rear is the same way but I haven't been back there yet to find out. I figured new pads were in order when I rebuilt the calipers. I was able to cleanup the original parts and re-use them so it ain't bad replacement parts. Bike had been sitting for years when I got it also, not that that matters but maybe someone swapped parts ???

JohnF