Brake Break Broke

So, the other day, I had to hop a flight to the Deep South, and the Sport was the designated mode of delivery.
Of course it was bucketting down as it does here in tropical northern NSW, so fully bagged up and 10 minutes behind schedule.... I backed out of garage and rolled off down my long step winding driveway.
At the road and throttling away I noticed some hesitation on throttle roll off between gears.... mmm dirty fuel??spark issue?? whatever it was, it's pissing down and I am heading towards late... and whatever it is, it's not happening under power, so let's go.
On the freeway - it's not far, and up to er, freeway speeds....  and the 'feel' disappears in about 10 minutes or so.
Another 10 and I'm rolling down to the round-about before the secure parking place, and surprise - I have no rear brake....
Into the storage garage and have a look and find

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Mmm, aaaaaah, "hurry up" says the take me to the airport guy so a quick couple of photos and away....
Did I really ride up the freeway with my foot on the brake?? Am I that stoopid??
After 2 hours to think about it in solitude, I decide yes, I must be!
A PM to someone in authority and a few back and forth reveal that it is a thing. The rear master cylinder can, with either crap in the fluid ( was changed within the year) or poor adjustment ( mmmm guilty as charged methinks),
and with multiple rapid applications - like going down my driveway in a hurry- pump up pressure and not release it back through the return valve/hole, and thus, locking the brake on.
Personage in authority also had access to a complete set off a recently deceased GRiSO, so a deal was done and parts shipped while I sat 1700 km away.

Returning to the north and gingerly riding home, tools out I find...

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Yep, that's the pad still there...

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Pad was kinda fused to the pistons, but with some persuasion...

That'll buff out, right....
I guess it was a very good thing that it was raining as heavily as it was, or I may have made the news!
Pity I didn't have a go-pro pointed at that direction, I'm sure it was quite colourful and entertaining!!

A big thanks to Mr Roper ( and Michael of course) for the parts and the intellect.
My rear brake rod in now a little bit shorter, and Big Red in starting to transform, part by part, into a GRiSO!!
( just a few more bits and the Don will be gone )

I'd just like to say, for the record...

Ay, Caramba!

I've had two Sport 1200's in a week that did the same thing!

Another bloke in Canberra had exactly the same thing happen. I was able to sort him out too with another disc and caliper off the *other* dead GRiSO!

If the rod is adjusted too far *out* it won't allow the system to bleed back into the reservoir so as the caliper heats up and the fluid expands it has no option but to press the pads harder against the disc and it becomes a viscious circle until the above damage is done!

Make sure when your foot is off the pedal there is a bit of free play before the rod starts acting on the Pistons!

Pete

Gee, I'd better check mine. Had my bike serviced very recently and the bloke took most of the slack out of the rear brake, as I previously had to push the lever down what felt like an inch or more before it would engage. I may now need to adjust to allow a tad more slack.

Is it an easy thing to adjust?

Yup, the plunger is threaded and has a locknut.

10mm spanner

Just checked it. Seems ok. Still a bit of slack between having no weight on the pedal vs depressing it against the return spring and feeling the engagement of the plunger.