It's good you found Anton Largiader's article on the oil canister. Snowbum has tremendous knowledge and experience, but his writing style is not what you'd call elegant. Fewer words and more pictures and diagrams would be helpful.
Measure the depth from the top of the filter canister to the flange where the filter cover plate sits (where the paper gasket was). It should be somewhere around 4mm. The idea is to compress that white O-ring a bit. The O-ring is nominally 4mm thick, but it can't hurt to check the actual thickness.
If your canister has a sharp edge, at least one shim is required. Sometimes two shims are called for, if you measure the depth greater than is typical. The shims are about .3mm thick. If the depth is small, you may need the paper gasket (to prevent the O-ring from getting squished too much). As I understand it, the paper gasket is usually NOT needed.
I think the shim (sometimes called a ring or washer) is part number 11-42-1-336-895. It should be in stock at any good BMW dealer. Maybe you're like me and don't live near a good BMW dealer? I order stuff from either A&S BMW in California or Max BMW in Hew Hampshire.
The white O-ring--the larger of the two--is the critical one. It keeps oil from bypassing all the bearings and going straight from the pump back to the crankcase.
The slightly smaller black O-ring is important, but not critical. It keeps oil from bypassing the filter.
EDIT: My R-100GS PD has the two O-rings, one black and one white, because there's an oil cooler whose lines attach at the cover plate. I'm not sure the set-up on your /7 will be the same. If it differs in this area, please disregard everything I've just written--except the part about the white O-ring and dimensions of the spot where it lives. This still applies.
There's also a small O-ring (like small enough to just fit over your finger, maybe) that goes on the bottom of the filter element. The filter usually comes with it attached. Sometimes it gets detached and stays on the little tube at the bottom of the canister when you remvove the old element. If that happens, you want to reach in there with something and remove it, because having two in there at once is not a good thing.
I can't help you with cylinder base gaskets and O-rings, other than to say, "good luck," and it looks like you have a fun project there.
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Pica Hudsonia screwed with this post 08-22-2012 at 05:00 PM