How much would it cost to road register a 250 2stroke or a 250 4stroke dirt bike eg yz/kx/cr?

If possible no more than any other motorcycle. The only catch is these are designed as off road machines. They won't p the emissions test for street bikes. They also do not come with a title like a car or street bike would. Most likely it would not be an option. You can check with your local DMV and they will let you know.If you can't would look for a street/trail bike like a DR650. Good luck.