Thanks for the info! got a question, I can only track down 3 oversized pistons. would it be possible to use 3 over size and 1 standard ? or would this unbalance everything ?
It's been done before as a last resort but not really recommended although i have had engines in that have had similar done ( 3 stock and 1 OS ) and were running just fine.
The OS piston would need weight matching to the others at the very least.
It may be worth searching some of the Japanese websites for pistons - due to taxation and insurance brackets 400's where hugely popular in Japan (hence the flood of 400 imports to the UK in the 80's - GSXR's, CBR's, ZXR's etc) "cruzinimage" don't list them but probably worth an email?