Yamaha V80/RC100 pistons. 52.5mm is a Rc100's Original bore size..

Below is the list of what your engine displacment would roughly be if the pistons are installed in a Yamaha V80

Piston X Stroke:

52.5mm X 45.6mm = 98.7cc

53mm X 45.6mm = 100.6cc

53.5mm X 45.6mm = 102.5cc

54mm X 45.6mm = 104.4cc