If heavier object have more inertia then a heavier yoyo would give you more time, or is it that between a 65g yoyo and a 70g yoyo there wont be a difference.
not necesarily. its all based on how the weight is distributed. you can have a 47g yoyo that spins longer then a 62g. it all depends on were the weight is distributed on it, if it is all concetrated on the rims, as in the 47, it will spin for longer then the 62, if it is distributed towards the center.
also, it’s a balance. think of newton. a heavier object is more difficult to set in motion than a light object and, due to gravity, will move with increased friction. if you had a 200g yo-yo, you wouldn’t have the ability to throw it as hard and its friction with the string would be more significant.
besides the weight distribution point, you’re playing with a balance between too light (not enough mass/momentum) and too heavy (too hard to set in motion/increased friction). (note that the bk2 is at 80+g the world’s longest sleeper, but that yo-yo is also very easy to throw).
I couldn’t have said it better than ed