Yes and yes. I've got an SL-100 that started as a simple tune up and ended up as a case replacement because the oil drain plug was JB welded in to fix a cracked case. I have an XL350 that I need to tear down to replace a mainshaft oil seal, but I have an CB1100F that I paid little for and has been perfect. Like the man says, "You pays your money and takes your chances"
That could be a spark plug, coil or spark plug wire, a blocked carb, or a something worse.
What's the bike look like otherwise?