I had insurance on my scoot for 2 years and used the insurance one time. they never asked about the speed of the bike. and mine was doing 45 easy.
General rule of thumb for insurance (applies to all insurance, not just auto insurance) is that the smaller and more straightforward the claim, the fewer questions the insurance company is going to ask before paying the claim. For a large claim, often the insurer will start to look for excuses not to pay it.
If you were to, say, lose control of your scooter and hit some pedestrians causing lots of injuries to yourself and others resulting in a large claim, your insurer very well might take your scoot to a mechanic to have a look at it. If your "50cc scooter" is suddenly revealed to be an "80cc motorcycle", you're likely looking at a denied claim because your motorcycle isn't covered by your scooter policy.
As others have advised, tell your insurer what you've done and get proper coverage. It'll cost you a few bucks more, but what's the point in having insurance if it might not be there when you need it?
