So here's the thing- 1st, 2nd, 3rd, 4th gear fine- loads of power all the way through to the red line. From 5th onwards, she just bogs down from 1/4 throttle onwards... I have had the carb apart more times than hot dinners- new jets and tang heights set... Plug is chocolate brown on a plug chop, so I don't think its a carb problem.... Could this be an ECU issue??

its true that the ECU does know what gear you are in.. actually there a wire for each pair of gears - going from near the gear selector around the back of the flywheel.. I think I saw it in the manual too.. are all those wires ok?

you dont think it could be compression related?

Not sure Mart- I have tried a few things. I will disassemble and check the gear selector wires and the ECU connector this weekend. I will also go back to starnard jetting and see what happens. Can't be compression- I have just rebored...