>>1824694>Actual dirt bikes converted to be street legal end up being very expensive or have engines that aren't designed to be riden a lot without constant maintenance.Sort of. Has more to do with the bike and the motor than whether it has a plate or not.
In the mountain states it's real easy to get a bike plated. That's what I did with my 525 - bought it as a dirt bike, put DOT tires/mirrors/lights on it, equipment inspection at state patrol, insurance for highway use, then some $$ at the DMV... walked outta there with a plate.
If you do that with the high-strung motocross "competition" bikes... your YZ's, CR/CRFs, etc... yeah, those want oil change and piston ~10hrs of runtime. They're designed for power on the track, and the transmission is configured for that as well. Real close ratio gears.
Trail and Dualsport categories aren't as high-maintenance. My 525 recommends oil change every 15hrs, oil analysis says I can go about 30hrs. Piston/top-end I do every other season or so. Still a race-oriented motor; it's not as much of a maintenance whore as a race bike, but it needs more love than an XR or DRZ does. But with that, I get another 10-15hp and lose about 40lbs off one of those bikes.
My Adventure is a 3000mi oil change, so it's more on par with maintenance like a car.
Either way, they're not hard to work on. I can knock out an oil change on either bike in about half an hour. A complete teardown/rebuild on my 525 takes me about 3 weekends.
Cost of ownership overall is on par with driving a car. You'll get better mileage, insurance is usually cheap. Tires are $100-200/ea, and those only last ~3k miles on a dualsport used on dirt+street. Less if you're really pushing in dirt/rocks.