I think the questions you asked are unnecessary. Just think about it and you will know that the flywheel on the left is left-hand, and the flywheel on the right is right-hand. Imperial system, metric system, wouldn't you know if you find a bicycle flywheel and install it? The pitch is even more useless. Do you want to process it on the lathe yourself? Then the factory should have a pitch gauge. Even if not, can you check the pitch of the outer wire of the flywheel or the flywheel on the rear wheel of the Little Dolphin (these two things you can There has to be something the same).