Picture this: bike starts as it should, runs smoothly as it should, charging light remains on as it should not. Tacho show the engine is running at about 750rpm (yes, 750rpm) when I know that it's revving at around 3,000rpm. Runs smoothly at those revs. Sweet!
Turn off the engine.
Turn the key to restart the bike (because I was worried about the charge light being on) and there is nothing...no warning lights in the dash. It just won't start; no clicks, no whirring or farting. Headlight works, indicators works, but not the stop light (handle nor foot pedal).

The 7.5A (top fuse) has blown.

Replace the fuse, went through the above routine, back to a blown fuse.

Battery is OK as it's always on a trickle charger.

Took out the brushes from the alternator to check for wear and they are fine (9mm exposed, 5mm is the wear limit).

Starter brushes replaced 5,000k's ago.

Forget the weeping master cylinder for the time being. I don't need brakes if it doesn't go!

Any help is appreciated.

Look at what the top fuse controls...
The accessory socket, stop light and bulb monitoring unit. It also controls the kill switch and the FI relay. No wonder that the bike cannot start.
The funny thing is that you were working on the front master cylinder and this is the fuse blowing up.
You should unplug the wire for the front brake and see if it makes a difference.
Let me know what's happen when disconnecting the front brake and we'll see from there.

Bert

Thanks Bert, I'll have a look tonight.

Bert, you ruined my life...

I was hoping for pages of posts from people all over the world, maybe some photos/diagrams, do this, don't do that, huge discussions that would go for days. My fifteen minutes of fame.

But instead, you say "You should unplug the wire for the front brake and see if it makes a difference."

You were right. It was the front brake switch.

How utterly boring.

Many thanks to you Bert.

Hi Neil,

Just be careful what you wish for. If you peruse the forum under bike not starting you will find a very extensive fault finding session which was unable to solve the problem. The bike in question was eventually repaired at great cost although the cure was and is to this day unknown and the same problem has recently re-surfaced resulting in a very good looking and very quiet K100.

Regards,

Phil

I just reverse your bad engineering

You did the right thing explaining what you were doing. If you had not given details, it would have been a real problem to troubleshoot your bike. Now, go back to work on your brakes. You will need them

Bert

It is a pretty good way to fix a problem and I use it a lot when I find a problem that did not appear before I started "fixing" it.
i.e. Was it doing it before? No?
What has changed in the meantime?
Coincidental faults are very rare so backtracking is very useful.

Regards,

Phil

Phil you are so right we have probably all done it, I know I have and when I backtracked found something I had done wrong which caused another problem.
Regards,
K-BIKE

Here is an update...triple checked the front brake switch, but I was still blowing fuses.
So I started checking wiring/connections/bulbs from the rear brake light and worked forward.

It was a pinched (and shorting) wire from the rear brake switch that was crushed when securing my footpeg bracket to the bike.
I think this came about in my haste to get the bike going after a spline lube.
Live and learn.

One problem with plastic insulated wire is when it is pinched the plastic slowly flows away from the pressure, sometimes over many months until the wire is exposed and shorts down. That happened here and I have seen it on other projects also.
Regards,
K-BIKE