Rebuilding motorcycle after timing chain skip 62K Km

Can’t put the pistons back from the bottom of the barrel. You have to insert them from the top, that means to disconnect the conrods from cranck shaft, a big can of worms.
 
It could be completely different with the 2.5s (I'd like to know for when I get to where you are), but on the 2.3s you can replace the pistons going in from underneath. You may have already explained why not on the new bikes, and I missed it (my bad).