+1 with Monte - drop and clean out the float bowls, noting any water or crud in there. Pay careful attention to the little tiny holes in the lower front corners - that is the fuel inlet for the carb enricher 'choke' circuit. If those are plugged/covered with crud you'll want to clean them out carefully with strong carb cleaner and a tiny strand of copper wire. (Wear eye protection so you don't squirt carb cleaner into your eye!) Also, take the air cleaner cover off and make sure you've got a clean filter with no rat's nest in there.
If non of these helps, yes, you should make sure that the valves are adjusted properly, because if the valve lash is closed up/too tight it will cause a problem of poor idling or not idling at all. We have to rule that out before going further into others things, or you'll just be chasing your own tail..
Post up a pics when you can!
-Mike