Yamaha Dealership w/ Unfair Payment Terms

A friend of mine wanted to buy his dad a motorcycle from Yamaha. They had 140k on hand to use for a down payment, and pay the remaining amount within a 3-year period, for a motorcycle that costs 186k. The dealership did not accept this payment term; instead they gave my friend 2 choices.

• Do a 1,2,or 3-year installment plan with interest
• or pay 140k, but my friend must pay the remaining amount within 14 days

I forgot to ask him what will happen if he can't pay said amount within that short time frame. This seems unfair and blatantly forcing you to get an installment plan for higher profits. Is this legal?