bike is in thana custody because of road accident

When an accident takes place, a case is registered by the Local Police. In your case as the person has died, the criminal case will attract Section 304 A of the Indian Penal Code which provides for offences relating to death due to negligence.Following an accident the police take both the vehicles — of the accused and the victim — into its possession when FIR is filed. The same would become  part of case property and the vehicle of victim is released only after giving an application in the court, which takes a lot of time.

Now, however,  as the Arun  Handa V.s Govt of NCT , the Delho High Court has passed a direction that in all accident cases, police would have to release the vehicles of victim after taking a surety bond and whenever it is needed, he would personally produce it (the vehicle) in the court and would not sell it.

Therefore immediately after checking antecedents of the person (victim) on the spot, verification of documents and taking a surety bond from the victim will release your bike.Hence you should make an application to police thereby asking them to release your bike.But if after checking the antecedents if police does not release the bike, then you can move an application before the Metropolitan Magistrate thereby requesting them to release the bike.