I'm really only replying because I seldom hear of a KLR with as many miles as mine. We're about even, at 95,000 miles/153,000 km.

I carry a diaphragm for the fuel petcock (with a rebuild kit) on my KLR. Never used it, but it's easy enough to carry. I've also taken to carrying two clutch cables following a series of failures. One stays zip-tied to the cable in use; the other rides at the bottom of a pannier. A spare tube (or two) is a no-brainer, and I bring fork seals and wheel bearings because I've got them. Sizes on the latter are pretty standardized, and failures aren't sudden, so carrying them isn't really crucial...but I once spent two days looking for fork seals in Bulgaria, so I learned my lesson.

Some other stuff I carry just to save the trouble of thinking about it or searching when I'd rather be sleeping late: oil filters, a pre-oiled air filter, a spark plug, and about twenty thousand nuts, bolts, washers, pins, circlips and other such. Oh, and a few valve cores: they go bad, you know.

That second chain thing sounds like a royal pain. I just buy another one a couple of thousand miles before I think I'll need it, then wait. They don't need adjusting for thousands of miles, and cleaning consists of spritzing with WD-40, then wiping with a rag if I happen to feel like it. They last 15,000 miles/25,000 km; why switch it out when a couple of spins of each nut adjusts it just fine?

I used to talc my tubes, until a mechanic pointed out to me that "talc" is really just cornstarch these days. Ever notice what cornstarch does when you mix it with watery gravy? That explained why whenever I patched a tube in the rain or after a river crossing it was always all gooey.

YMMV.

Mark

Edit to add: I looked at oldbmw's post again. If I want to change out a chain I need to loosen (i.e., un-adjust) it and pull my axle, or remove a link. Is that really worth doing before the chain wears out one or two continents later?

To make things clearer, my bike is an Enfield Electra and there isn't room to use x or o ring chains, so they are a bit labour intensive using the old style chains. By running two from start, I can just unclip the split link and I use the current one to pull on the replacement, takes about 2-3 minutes. no need for any spanners or adjusting. On a new chain I can usually manage about 3-5 K miles before I need to do this. chains have a working life of 6-10K miles. If only they left enough room for a modern chain. The bad side is any chain fitted to an Electra HAS to be split link type as it is necessary to dismantle all the primary drive to get at the gearbox sprocket. saying this I now realise that changing x or o ring chains is a lot more work than a split link chain.
What I offered as advice, whilst good for my set up may well not be the best thing for a more modern bike
My next bike will be shaft drive (one good thing about the BMW) unless I fall over a nice Meriden Triumph