[Andy B]

I'm going to assume that you have the low side of the side-pot more or less locked up. By betting, you're basically laying $10 to $8.50 that the other guy will fold a better high. He's not folding a better low, and he's not folding a decent high hand. He might even call down with a little pair. Since he's gunning for the main pot as well, I'm guessing that he's calling with about anything. Also, by betting, you open yourself up to a check-raise. I don't like the bet.