Hi Harry, welcome to the YOC. Sorry to hear about your problem mate, just a suggestion tho, you have no electrical problems as it starts and runs so it's almost certainly a fuel air mix problem, you seem to have fixed all the other things it might be so that only really leaves the fuel. Not sure with these bikes if they have crank seals cos some of the lads on here say that crank seals can give this type of problem, usually when they bog down like this it's to much air so check for leaks around the whole of the inlet side of the fuel system, good luck mate.