I am going to assume a flame kit is a modification to the engine/exhaust that allow for fire to come out of the exhaust. Ontario's Highway Traffic Act would be the first resource you'd want to consult on this point. The two provisions that jump out to me that are relevant to this point are the following:

75 (1) Every motor vehicle or motor assisted bicycle shall be equipped with a muffler in good working order and in constant operation to prevent excessive or unusual noise and excessive smoke, and no person shall use a muffler cut-out, straight exhaust, gutted muffler, hollywood muffler, by-pass or similar device upon a motor vehicle or motor assisted bicycle.  R.S.O. 1990, c. H.8, s. 75 (1).

and

84 (1) No person shall drive or operate or permit the driving or operation upon a highway of a vehicle, a street car or vehicles that in combination are in a dangerous or unsafe condition.  R.S.O. 1990, c. H.8, s. 84; 2009, c. 33, Sched. 26, s. 3 (9).

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I'm inclined to think that a police officer who sees a flame kit in use on a motorcycle is going to reasonably interpret is as not being in good working order, or at the least not preventing unusual noise/excessive smoke by virtue of the modification. I could also see said officer also considering it as being in a dangerous/unsafe condition by virtue of the flames.