GS(A) ones this time:
Driving on motorway and smelled petrol - pulled over, stopped engine and popped bonnet - no sign of anything wrong.
Started engine again and took another look - the fuel line had split just before the carb and was spraying petrol directly onto one of the exhaust manifolds.
Scary since if I hadn't pulled over to check it would have gotten worse.
Sorted that one out by using a spare jubilee clip to tighten up the hose connection.
Going along once and pressed the brakes and nothing happened - well not quite but the usual brake performance was well off.
Turned out that
was spilling from the top of the engine (a pressure relief valve if I recall) and spraying over both inboard brake disks.
Once I got into a GS during the winter, started the engine and the revs rose, and rose and rose - this with my foot off the pedal! I removed the key at around 6k revs - a little below redline.
It seems that water had gathered in the carb air inlet valve sleeve and me pressing the throttle just a little (it needed that to start) was enough for the water to freeze - after which the throttle pedal was pointless since the carb was stuck.
Taking the key out and waiting for a few minutes (plus spraying the carb area with WD40) cured that.