The past tense of bite off more than one can chew is bit off more than one can chew.
The third-person singular simple present indicative form of bite off more than one can chew is bites off more than one can chew.
The present participle of bite off more than one can chew is biting off more than one can chew.
The past participle of bite off more than one can chew is bitten off more than one can chew.