Help needed guys, using my brothers 1150 Gsa at the mo and its developed a totally random cough/splutter when hot between 1500/2600 rpm. It can be on a left or right turn and pulling away. I thought it may have water in tank as filler drain was blocked replaced filter check petrol. Checked over electrics all seems ok. Any ideas before I start buying bits, any help will be received with seems like something braking down when hot?.