This is something that has been puzzling me all month.
As you're probably aware, my ZX-4 blew up on the 31st of December (yeah, fuck you too, 2013!), and I'm trying to work out why. And how! How could a bike travelling at 70mph through cold air overheat? It's a watercooled engine, true, but why would it blow up at that speed? It would be more understandable if it had been in town, but not, this was on the A303, braking for the Andover slip road (seeing a friend). And the speed at which it blew up concerned me too - one minute it was registering just above stone cold, and then within under 10 seconds, the needle was registering the red zone. The knocking noise followed soon after, and now the entire coolant system smells of burning rubber.
I won't be able to get the engine off to strip it for a while, so does anyone know what would cause the bike to overheat so dramatically to give me places to look? The oil/water pump idea seems to have been a red herring - when the mechanic at Hatfield drained the oil, there was nearly no contaminatio, aprt from what would be expected from a bike that had been standing a while. Looks like the head gasket is OK too.
The rad fan, on the other hand, has half melted!!