Terry, around these parts $50 a hole is the general going rate for boring the cylinders. The CB400 466 kits is only $120 but, like you say, the expense comes in when it's another $200 to bore. Don't know about the 836 kit for the 750, but the 466 kit leaves almost no taper at the bottom of the sleeve making piston installation a pain. Anything bigger in sleeve would require machining of the bores in the cases also which I think would be even more expensive than the cylinder boring.
Yeah mate, 50 bucks a hole is fairly common here, but that's for only a couple of passes with the boring bar, for 1st or 2nd oversize. Probably around 2 hours work to do a rebore for 1st or second oversize for an SOHC4.
My old Repco boring bar will only do 10 thou max cuts, so if you wanna go 4 mm (160 thou) that's around 16 passes on the bar per cylinder, (over 1 hour per cylinder) or I pop the sleeves out and hog 'em out to 64mm on my lathe and then reinstall them and bore the last 1mm (4 passes) on the boring bar to get them perfect.
My machine was only ever meant to do little singles or twins, but I have used it to bore out a set of Suzuki GS1000 cylinders to 1085cc (73mm) with good results. To get it to machine the inside cylnders on a big four I need to slide the bar out to the max on it's stand and I always worry that it might affect alignment, so yesterday I chopped a damaged CB750 cylinder block in half on my band saw and heated it up in my industrial oven, (I'd never press a sleeve in or out Ron, that's asking for trouble IMHO) then dropped a sleeve in, and once cooled, I bored it, and it "feels" better with the machine slid all the way back on the stand, but that might just be psychological, ha ha! Cheers, Terry.
