steve p wrote:was it welded like your spark plugs SC?

Some people have a sense of humour, you on the other hand, well lets just call it a mean streak.
I think the best way to say it is that, due to having been ridden in all weathers (like all bikes ought to be able to be) the exhaust had seen some serious heat cycles and plenty of rain and even snow, thus accelerating the deterioration of the flanges, studs and the areas closest to the cylinder heads.
The plug was simply down to the fact, I neither believe in paying dealers exorbitant prices for shit services (nor could I actually afford them even if I did think they were worthwhile) and the "plug issue" was simply down to me not checking the actual condition of the plug in the head, due to the fact that it had carried on working.Only when I decided, time had finally come, to actually remove the plug, did I discover that, it was basically working on a wing and a prayer.Having to do a reasonably big stripdown and a head off job, was educational, if nowt else.
In other news, I spent the last 3 days getting an old ZX7R (that hadn't been run for 3-4 years, which would sometimes turn over but wouldn't run for more than 1/2 a second) up and running (changed all four plugs and bought a new battery) and after a serious clean of the air filter, drain of old fuel, good pump through of Motul engine cleaner and some pro FST for good measure (that was for old times sake as I realise that's more often used for carb icing issues), test of vacuum valve, vacuum switch,ignition coil check and clean, fuel filter strip out and clean, fuel pump strip out, clean,test and a pretty comprehensive stripdown and clean of the carbs, jets and needles out, cleaned, inspected, all put back together with no left over parts and now a bike that runs cleanly on all four cylinders and even idles correctly with no throttle.
Now I can get rid of it.