dont even bother with the jet kits, just order up a range of jets from jetsrus.com. I got every size from 240 to 320. Then its just down to tuning.
For your original question, it would be purely up to the jet that was in your carb. If the jet is too small it could cause the engine to run lean and seize it. If the jet was too big, then you'd just be running it rich. The worst that could happen there really is the plug fouls out.
the airfilter is just more exposed to mud and water with the lid off. You should be cleaning that thing by hours of run time, not miles. Your top end would be long gone before you even would think of making it to 30,000 miles. Not to mention all the other stuff that would be worn out.