How do you guys like my forum? What could be improved?
You have a very good domain. Having said that, I don't really like dark themes. If you wanted to keep the current theme you are on, that's fine, but I do recommend some changes at least. Custom Icons will do very well for your forum and is the easiest way to customize a theme/style. Currently, images like this one can easily be replaced by something that potentially could be more about Power Sports (a little cartoon ATV or a real one would work perfectly).
Your logo's text is hard to read and it's hard to see what's going on in those images. The idea is right there, you just got to make a similar but clearer-looking logo. After looking at the kind of forums you have, I see the purpose of each one of them, but at this point, you don't quite have enough activity to have that many forums... yet. Either you could merge forums together or make subforums, which also works pretty effectively as well (this would especially be good for your ATV brand forums). Other than that, there isn't much else I can say. You have a great idea, but you just gotta take the time to make it all work out.