Gen 1 Fazer cutting out / dying

[MrL]

Thanks for the answers so far guys. The bike has been in regular use the last few months, and when it is ridden normally does 170 miles a day.
Last week I noticed a slight hesitation around 9 - 10k revs but it pulled through it, I thought maybe a carburation issue ?
Today however it was a complete loss of engine instantly when it got to certain revs when hard on the throttle, different in every gear. Like hitting the kill switch. When I backed off the throttle the engine came back into life and ran fine.