You can check to see if the motor dirt bike had liability insurance coverage on it that would cover the damage the driver of it did to your vehicle. If the bike did have insurance then you should make a claim through its property damage liability coverage.

If the dirt bike did not have insurance on it then you can turn the claim in with your collision coverage or go after the at fault party to pay for the damages. You will need to pay your deductible if you make such a claim with your own insurer. You may ask your agent or claims adjuster though if they plan to subrogate with the at fault party and if they will be able to recoup your deductible when doing so.

Your other option would likely be to take the driver and/or dirt bike owner to court and try to get a judgement for the cost of the repairs to your vehicle. A lawyer familiar with your specific state's laws may be able to offer advice on your situation or you may try contacting your state's insurance regulator for consumer advice.