Service time...

Well, now's as good a time as any to do a bit of a service!

This is one of those things that's unnecessarily complicated and fiddly on the Norton, but whatevs, that's just the way it is.
I have long felt that if Norton had stayed continuously in production, the Commando could have evolved in much the same way the Sportster has, keeping what was good and improving what could be better. Interestingly, the engineers who designed the clutch (and I think gearbox) for the Evolution Sportster came from Norton, and had designed the same components for the Commando when it was launched!
But I digress. On the plus side, doing an oil change on the Commando is bizarrely satisfying...
First of all, you will need several copper and aluminium washers. Some of the copper ones you may be able to anneal and re-use, but be sure to have it all ready before you start:

Few people do this, but it wouldn't be a bad idea, once the oil tank is drained, to remove its inner metal filter and wash it in some clean petrol. Chances are you'll find a lot of sludge there.

In this particular case, the filter is shiny-clean so I'm not going to bother taking it out this time, but that shows it's worth doing once in a while: last time I did an oil change I had taken it out and cleaned it well. That, plus a good oil with a good cartridge filter means all the lubrication system will stay cleaner, longer.
If you do take the tank filter out to clean it, you must use two new aluminium washers (042065), or that sucker will leak.

The reason my oil tank is empty is that the bike sat unused for many months and the oil gradually fell into the crankcase. Wet-sumping can take as little as a week and is totally normal, not a problem. The single most effective remedy is to ride your motorcycle often and regularly, just the way it was meant to.
We'll take a look at the oil tank drain in the next post.

Drain the crankcase as thoroughly as possible. I have the latest type, with both the large sump plug and the smaller one at the front.

Look, I know it's probably supposed to be a 9/16 AF wrench, but really a 14mm will fit perfectly. Both bolts have a magnet, which you should inspect and clean (motor oil is extremely hazardous stuff that should not come into contact with the skin. Wear gloves and dispose of it responsibly):

The large plug contains a gauze filter: in the proudest British engineering tradition, it all comes apart to reveal far more components than you would reasonably expect, and all should be cleaned and put back together.

Above, from left to right, the cleaned components are shown in the order of assembly.

For goodness' sake make damn sure that circlip is seated well... a massive crankshaft is spinning furiously just above it. And of course to remove the sump plug in the first place, and to replace it, you will need a rather large socket:

Something else that is very important is the large sealing copper washer, which must be replaced each time. They compress significantly when you torque down the sump plug, because they actually contain a sealant, which gets extruded when the washer is compressed and is only good for one fitting. Reusing an old washer means your crankcase will leak. You can see the difference between a new washer and an old one here:

With the crankcase and oil tank drained, with all fasteners back in place and torqued down, you can move on to replacing the filter cartridge (if you don't have one, I would strongly recommend you fit one, as well as an oil cooler if you live somewhere warm). Witold helped me do this last time with a strap wrench and some sand paper to improve grip. A long lever is also very helpful.

At this point the battery on my camera ran out, but I carried on with what I had to do, so the photos in the next post will be as fait accompli.