Low power full throttle mid rpm

[vinnyb]

What is winterising the carbs? My bike has lived outside in all weathers, summer, winter, sometimes sat for 2-3 months at a time. I've never bothered doing anything with the carbs and never had a problem with them...

The problems I have had are around corrosion of the caps and plugs. It happens every year, as water sits around the top of the engine. It does exactly what your describing. Misfires at full open throttle. Back off on the throttle and the revs pick up.
It's to do with having a week spark and as the resistance of the air fuel mix changes it misfires.

It's a lot easier inspecting your caps and plugs then taking your carbs apart.

I think Ministras means adding fuel stabiliser to prevent the fuel breaking down over time while the bike is stood. Have you tried ACF50 around your plug caps and plugs it should stop that happening.