I have a couple of stuffed chonda�s on the shelves so I will take a disk out and replace it. If memory serves correct I am pretty sure they are exactly the same size and thickness.
So if the disk does not solve the problem I think it has to be rings as well.
I managed to find a reasonable set on ebay.
http://www.ebay.com/itm/Piston-Ring-52mm-For-Honda-HR17-HR173-Mower-EG650-EM500-EM500K1-EM600-Generator-/272285311822?hash=item3f6578234e:g:KD4AAOxytdlRAlJT&vxp=mtr
I can seal the case up with selastic if I crack it however I have very little doubt the head gasket will not crack upon being removed from the motor no matter how careful I am.
If the disk doesn�t solve the issue I am thinking this might turn out to be another parts mower.
I�ll let you know how I go with a disk.
Any thoughts on re-ringing would be appreciated.
Jaffa