All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
If the money that is invested in business reaches the Nisaab, i.e. the minimum amount that is liable for Zakat by itself or with other money that is added to it, then Zakat has to be paid on it.
The minimum amount that is liable for Zakat is what is equal to 85 grams of gold after one whole lunar year (Hijri year) elapses on them; that is 2.5% of the capital money and profit after deducting the debts. If the money owner cannot pay the Zakat after one year has elapsed because he does not have enough money at hand, then he can delay the Zakat until he has money and then pay the due Zakat for the previous years.
Therefore, you are not obliged to sell your motor bike to pay the Zakat, or to borrow money for this purpose.
Allaah Knows best.