No, I don't think someone who "doesn't like obamacare" is racist for that reason. I just think they're badly misinformed. They're either completely misinformed about what's in it, or they have no idea what the alternative was. They have no idea how many millions of lives have already been improved. They have a tendency to disbelieve objective facts, such as that people died because they couldn't afford to go to the doctor.
That to me is the hallmark of the remaining Republican voters. When facts are pointed out that are really bad (such as statements from Paul Ryan's description of his own budget) they say "that can't possibly be true, so I don't believe it".
The main reason stated why people don't like "Obamacare" is that he incorporated mandated payments, an idea put forward by Republicans. There are plenty of speeches on the record by people like John Boehner about what a wonderful idea mandates are. Heck, there are plenty by Mitt Romney, since he put them in the Massachusetts plan.
So it's not necessarily racist when those VERY SAME people start screaming about how THEIR OWN IDEAS are unconstitutional, socialist, destroying the fabric of society, etc. But it certainly isn't rational.