So my bike (2015 650) won't start easily. The engine turns over when i press the ignition button. Excuse my lack of knowledge of technical terms, but when I turn the key and the dash lights up, I then turn the kill switch to on, and there's usually a slight whirring sound after I turn the kill switch on. Whenever this sound happens, the bike starts just fine. But sometimes when I turn the key and press the kill switch to on, there's no whirring sound and the bike turns over but wont start. If you have experienced this or you know what the problem, I'd really appreciate it before I go around replacing spark plugs and batteries and what not. I did charge the battery and it started quickly afterwards so I think the battery might be fine. not sure about spark plugs, havent checked them (dont know how to). Is there anything else that could cause ignition problems?