The two basic rules to start with are:
1. you must have a reasonable expectation of profit in order to take writeoffs
2. you can only write off the business portion of your costs. If you also derive personal benefit from the expense, you must allocate a portion to non-deductible expenses
So, at a general level, you could likely take some writeoffs against motorcycle expenses, if you have a business which has an expectation of profit and you account for your personal benefit in claiming expenses.
1. you must have a reasonable expectation of profit in order to take writeoffs
2. you can only write off the business portion of your costs. If you also derive personal benefit from the expense, you must allocate a portion to non-deductible expenses
So, at a general level, you could likely take some writeoffs against motorcycle expenses, if you have a business which has an expectation of profit and you account for your personal benefit in claiming expenses.