Sorry to hear you damaged the bike - while in the process of claiming about the corrision. I also kept my bike clean etc. Yamaha are not some tiny operation - they produce marine machines as well and I am sure they are on top of chemically treating their engine metal - so I don't buy the "resignation that this problem is beyond sorting" that might be being perpetuated by dealers (to put anyone off complaining about the problem). I had a look around the other bikes at my dealers and none of them showed the extent of corrision that mine has! This is probably something to do with the manufacturing batch - your bike might have been one of the same batch!

Regards,
Tomo7