No, unfortunately, you almost certainly cannot terminate your lease. If the landlord is fulfilling its obligations, then you may generally not terminate a lease due to the actions of third parties not under the landlord's control. Also, a landlord does not have an obligation to affirmatively disclose, without being asked, what third parties do on their own property, so the landlord's failure to disclose the dirt bikers does not constitue fraud. The only way you would seem to have grounds to terminate or void the lease would be if you, prior to leasing, specifically asked the landlord about the noise levels in the neighborhood, espcially if indicated that this was a concern of yours--if you did, and the landlord lied in answering the question, that lie could constitute the sort of fraud that might let you void the lease.Speak to a real estate attorney:1) If there are any noise, safety, or zoning ordinances which the dirt bikes violate, you may be able to take action on those grounds.2) Even if there are no ordinances, if the dirt bike riding is clearly inappropriate for the type and character of your neighborhood, it may be possible to bring a "nuisance" action against the lot's owners.