Good idea, those things have been an issue for as long as they've been around. It's good that they weren't on every 450 and 750 during that period, and I've never been sure why they were only on some. Looking at parts fiches, it seems a slightly different version of the oiler screw was on the CB750K0 through K5, and Honda started putting them on the CB450K3 and it shows the oiler through K6. On the CL450 it seemed to start at K0 and ran through K6. But I know I didn't see them on all of those models, so it must have been random to some extent (there wasn't one on my CL450K5). But they always allowed a little oil seepage no matter what you did.
