All pistons are still available, it's just that getting them at a good price is not so easy these days as supplies are drying up. To our knowledge Honda will continue to produce these parts, but there's a slim chance that like the old RS125 piston they get them made elsewhere and the price trebles. Worrying!!

As for this piston in that cylinder......I've used every conceivable permutation at some point with no problems, but it's just not the textbook way of doing things.