It's a breach which may be a curable breach under the loan documents.
The question really becomes was the breach cured. In other words, did the person ultimately pay. If the loan documents state that the Lender doesn't waive the right to declare untimely payments a breach then a breach could be called a default and the motorcycle could be repossessed.
If the Lender accepts the payments late and the language doesn't preserve the right to call a default then the payments and acceptance are a waiver of the right to declare a default.