Especially if you havent ridden if for a while (be it a week or a month).
Do check your oil, or you would be with a fried engine. Yesterday thankfully i checked my oil, i was 1 and 3/4 of a quart down (nearly 2 quarts) out. I dont know if it was like that the last time i rode it. I had been complaining of a weird smell and i noticed a leak on the lower gasket, but i dont know if that's the cause. I went on a 20 mile ride yesterday, i will check the oil tomorrow to see if its gone down again..
Also check your tire pressure, chain slack, and the fuel quality and battery too.
I noticed that when the bike is left alone, it starts but it idles like shaZam! until it burns off the bad fuel in the carbs before it starts to rev properly agian. Mine makes some weird 'misfires' as the crud goes thru teh carbs before it revs freely.
atleast it runs.. im happy.