[fizzwheel]

Just because the optimate says the batteries OK it might not be. You're describing classic flat battery syndrome, i.e. lights work, but bike buzzes when you try and start it.

First thing I'd do is put a voltmeter across the battery and measure the voltage. If you do a search there should be some more detailed explanations as to what to do. I wont describe it as I'm not that technically minded.

Also the other thing to do if its been stood for ages, is pop the tank off and drain all the fuel out of it and fill with fresh, you might want to think about taking the carbs off and cleaning those out to as unleaded "goes off" and it can leave behind a gummy residue which gums up the works.