I suppose the sun is uncharted territory, so here's another sunset, near Iringa, across the farms of the rural Southern Highlands.

There seems to be little time for rest on this trip - will have to do something about that. First, a note about my recent route.
On departing Nairobi in the direction of Uganda, quite some time ago now, I left the "London to Cape Town Main Route," and have seen hardly any overland travellers since.
When I reached Morogoro about a week ago I joined the Dar es Salaam to Mbeya road, which brought me back onto that main route.

And a few miles after Morogoro a fully loaded BMW passed in the opposite direction, with a white rear number plate - so maybe German.
But as they say ........... BMWs don't stop.

And then, in Mikumi, I bumped into two Swedish riders, on a KTM and a ..... oops, I forget.
But what a small world! They must have been following and catching up with me the last few weeks, as they too left Nairobi towards Uganda and have been through Rwanda and Kigali as well.
"It's a great route around Lake Victoria. But dust and face powder up to your elbows on that road! Diabolical!"
They liked the Uganda route as much as I did, and found the same awful road as me, agreeing that it was worse than Moyale (although much shorter).
"And haven't seen another overlander since leaving Nairobi."
Me neither. (Then I met the two British cyclists a couple of days later.)
They were just leaving a petrol station and heading for Iringa, travelling at twice my speed, expecting to reach Cape Town in about six or eight weeks.
So I'm back on the main haul (for now), and have been busy with the bike.

Back whenever it was, when I inspected and temporarily repaired the chain roller (in Kigoma if I remember right) I also noticed that the gearbox sprocket won't make it to Cape Town. It's too worn.
No problem, I have a new spare. One tooth smaller at thirteen, in case lower gearing was needed anywhere. (It was, in the Western Desert, but I'm glad I didn't fit it there).
So I took the plunge the other day and changed it. I say "took the plunge" because these sprockets are attached with what is usually known as "Yamaha's b***dy great nut," which can sometimes, or often, be next to impossible to remove.
(As was the case on this very bike when I replaced the gearbox internals before departure. I had to drill and split the nut, finding the thread underneath had been flattened by "previous servicing!")
First I looked around to see if there was a garage with a compressed-air spanner tool. One of those will usually remove the "b***dy great nut" if it's troublesome. But there were none.
So I took the plunge and used my little tool kit.

I had taken the precaution, before departure, of not tightening up the nut to "Yamaha's b***dy great torque." Well, as far as is possible, because I've never owned and hardly ever used a torque wrench. I just tightened it an amount that seemed right for the small engine and "Yamaha's b***dy great tab-washer" that holds it nicely in place. Which needn't be all that tight, in my opinion.
And joy of joys - it loosened without putting any enormous strain on the secret method I use to stop the rear wheel turning on application of my little "b***dy great spanner."
So that job is done, and really, the one tooth less on the sprocket makes next to no difference and would have been a waste in the Western Desert. More teeth on the rear sprocket as well would have been needed to make any useful improvement in the sand there.
By the way, I found a significant portion of the Western Desert crammed and compressed between sprocket cover, sprocket, and gearbox casing. It all fell out, congealed and solid with old oil and cocoa powder, onto the nice lawn of the place I was staying in. Had to clear it up smartish before it got trodden into people's tents.

And the chain roller is as before. The bearing still rotates, the rubber is still there in more-or-less the right place, so it's still more-or-less doing it's job. While changing the sprocket I inspected the "damage" that was done to the sprocket cover when the bike was running without the guide roller in Egypt (and maybe before). I don't think it's an issue if the roller is removed. The cover is soft aluminium and has just been distorted a bit by the unguided chain. (Which is a pretty substantial size for a 250cc. Don't remember the size, bigger than my Honda 500, maybe the same as the Dominator 650cc).
But the roller is still there for now.

That job was followed by the usual chain-oiling, and oiling the clutch cable, which I find collects a lot of dirt and dust and slowly seizes up. It did that on the dirt road on the way to Mombasa, feeling as though strands of the cable had frayed and were jamming up the clutch action. But it was just lots of dirt and sand.

Then I saw the thing we all dread seeing, but that we're supposed to look for nearly every day - the empty hole where once a bolt head lived.

This one was supposed to hold the exhaust pipe to the frame - one of only two bolts that holds the entire exhaust in place. So with half of them gone a fair amount of extra stress was probably being exerted on the joint between exhaust and engine.
So it couldn't be ignored and led to a journey into the entirely uncharted territory of my "Margarine tub of Nuts, Bolts, Washers, Clips, Brackets and Pins," that lay undisturbed until now at the bottom of my luggage.

The bolt was quickly replaced and I'm continuing on the road to Malawi, now stopping in Tukuyu for a day or four, with, I hope, everything securely attached. Here, an oil and air-filter change will be needed before I continue to the border. The work doesn't seem to stop just now.

Oil consumption has been increasing steadily. It's still OK, but I have to top up twice between oil changes whereas before departure it was zero times.
Beau's bike was the same. And seeing the constant dust clouds kicked up by the traffic on the roads, and the sand in the Sahara, I've become convinced that the simple oil-impregnated foam airfilter fitted to these bikes isn't really up to the job on this sort of journey. Probably dirt has been getting into the engine and increasing the wear rate in the bore.
It's become common now to see van and truck drivers using compressed air lines at garages along the road to blow all the dirt out of their paper cartridge-type air filters. I think these paper filters are really needed in this sort of environment, but one of sufficient size would be too big to fit on a little bike like mine. So I'll have to increase the frequency of cleaning the filter, and probably increase the amount of oil I pour into it each time. Oh dear - it's such a messy job!