So here goes for a first post, A few weeks ago I was out for a ride on the old girl everything was running sweet, revved it to maybe 17k in second gear and when i changed up it no longer wanted to rev, make any power etc. Pulled over to the side of the road, no obvious windows in cases etc. Engine would still start first go on the button, no overheating, would idle at a decent rpm however it just sounds like its running on 3 cylinders and does not want to rev or make power over 9-10k. Rode the bike home parked it up and began working. So far have replaced all spark plugs, were a bit rich but nothing crazy, no melted pieces of metal or anything stuck to them. Have stripped, cleaned and rebuilt carbs, and have redressed the ignition leads. So I'm a bit stuck and was looking to see if anyone has maybe any idea where i should go for troubleshooting next as im the first to admit i dont know everything. Please find attached a video showing how the bike is running.