Been mulling over ideas a lot recently and I think I have settled on my plan of attack for this old beast. I am pretty sure the pistons are well f*cked and after looking up the priced for FZR 400 pistons rings they can get stuffed! Jesus those things are expensive. So, overboring seems to be the way to go! 59.00mm x 40.50mm = 442.90cc (+3mm bore = FZR600 pistons) Hmmm... FZR600 Pistons heeey? A lot easier to find and piston rings are much more affordable. I have done a bit more work on the heads, but that's for another post ;P Thoughts?