With a non-turbo gasoline engine there are two paths for oil to get into the combustion system: Valve stem seals, and piston rings.
If you go back to the 1970s and early 1980s, plenty of Honda engines had issues with valve stem seals. My '78 Civic used a litre of oil every 400 km towards the end. It belched grey/blue smoke if you revved it too high. This was a lean-burn CVCC engine, which was high tech for the time. Sometime in the 1980s Honda figured out how to do valve guides and valve stem seals and this has rarely been an issue since.
This leaves piston rings. The cbr1000 uses coated aluminum cylinders which are integral with the upper crankcase, as do most late model sport bike engines. But there are a ton of variations in what that coating is and how it's applied, and how the desired surface finish on the cylinder walls is achieved. There is pressure to make that surface as smooth and mirror-like as possible, because it reduces friction. The disadvantage ... is that it's harder to achieve a good mating between the rings and cylinder walls (traditionally "break-in"). If both the rings and the cylinder walls don't achieve just the right amount of wear during the initial running-in period ... the engine will be an oil-burner because the scraper parts of the oil control ring set won't adequately scrape the right amount of oil off the cylinder walls.
I have a little bit of personal experience with this ... my '04 ZX10R has been an oil burner (about a litre every 1200 - 1500 km) since overhaul about 20,000 km ago with new piston rings. The problem I had was what to do with the cylinder walls. I know what to do with cast-iron cylinder walls and I've done that many times. The shop manual is of no help ... measure for tolerances and if out of spec, replace cylinders (i.e. replace the entire engine block), it is silent on what to do with the cylinder walls to achieve a good surface finish. The cylinder walls were visibly mirror-finish. I got contradictory advice on what to do, so I opted to do what the shop manual said ... Nothing. If that didn't work I could theoretically always pull it apart again and hone them. On the other hand, if I honed them and shouldn't have, the engine is finished. So I did nothing to the cylinder walls ... and it never really broke in. The engine runs fine, but it uses oil.
As far as I know Honda has never admitted what the exact nature of the problem is with the cbr1000 engine and there has certainly never been a recall. It's pretty likely that the problem is the same as what mine has ... cylinder walls that are too smooth to consistently break in the piston rings.
Honda probably doesn't want to have a recall on this ... because the only fix involves replacing the cylinder block and that means a COMPLETE teardown and rebuild by a dealer-level mechanic ... or a complete new crate engine from the factory (which would be a more reliable solution - but for some reason the bike manufacturers are far more reluctant to do the crate-engine route than the auto manufacturers are). Either way, a recall to fix this would be expensive.
It's anyone's guess why the cbr600 is good (never had this issue) and the cbr1000 has this problem ...
