you say it cuts out when turning out of junctions,i would suspect the wiring around the steering head in particular the ignition wires & any cut-out switch wires,as the cabling in this area is always moving and bending with the steering & single wires can break down.What happens when you turn the handlebars with the bike ticking over on its stand, does it still cut-out? if so then a continuity check of those wires will find the fault.
Chris P.Duck
October 2010