Yes, you can lie and cheat and probably get away with it. if you don't do it convincingly enough the bike will likely be confiscated and there will be the option of further prosecution. You will also be marked for the future and you can expect thorough searches everytime you cross the border.

If you are taking your own bike (or any item with a serial number for that matter) across the border you are supposed to carry proof that it was acquired in Canada (receipt, green card etc.). So depending how sticky the border agent is merely playing dumb, as suggested by some, may not work.

Staying 48 hours gives you $700.00 (CAN - including local tax pd.) of goods which can be brought back duty free (although they can still charge GST & PST or HST). But if a single item is more than that I don't think it qualifies as a 'deduction'.

I realize the O/P wasn't asking for tips about how to cheat the system, just information about taxes and duty. Check out Duty and Taxes Estimator for an estimate of duty and taxes. Note that a lot depends on where you reside in Canada and where the bike was made. Somewhat bizarrely I don't believe there is any duty on bike parts - even including frames. Go figure. But those are the rules.

Why not check out the duty/tax situation (probably minimal) and just decide whether or not the bike is still a good deal factoring in those costs? That way you don't have any worries crossing the border and you can still look at the guy in the mirror as an honourable person when you shave in the morning. I'm really sick of those who love Canada and our "free" health care and social programs but are willing to do anything to avoid paying their fair share.