1990 fzs600 black smoke at high revs

[gav245]

Went to northern ireland last weekend, bike ran perfectly but on the way home it started blowing black smoke and bogging out at 8000rpm.
Ive adjusted valve clearence, changed oil, spark plugs. I took the end can off, some of the baffles came out so changed the end can. Adjusted the carbs but its still black smoking.
 Anyone had this problem ? Please help as i am really stuck with it.

[daviee]

black smoke is flooding check your carbs are not leaking or even a loose main jet

[gav245]

Thanks for the advice, i will look into it

[Trebus]

Air filter / box checked for blockages?

[gav245]

Checked it, its clean and theres no blockages

[Fazerider]

Black smoke could be oil. If the airbox is clean then it probably isn't getting in from the crankcase breather, which makes it more likely to be a knackered valve stem seal.
Can you pin it down to a particular cylinder by looking at the state of the plugs? If they all look the same then it'll probably be an exhaust valve seal and taking the downpipes off should identify which cylinder.