lots of good comments about mechanical side of things but none of these should stop it actually starting or at least attempting to start (other than the obvious timing) . that said friend of mine with a Goldie drove himself round the bend chasing his tail till he found melted alloy under one of the valves (he has cooked a piston and blew a hole in the top) ......but that was a single........like i said to him 'well the melted alloy has to have gone somewhere"
so lets take a look at some of the obscure stuff
pretty high up my check list would be stale fuel ( you said, i think bike had been off road for a bit) ....sorry if you have already filled it with new fuel, ......try disconcerting the tank and filling just the carb bowls with some new fuel ......if it still doent at least fire up i would be starting to look for electrical faults
like they say 80% of carburation problems are electrical