If you are still having problems with your bike then give us a call (ECO Industries Ltd) based in London and perhaps we could assist you further - we are Loncin agents and could help you with servicing, repairs or spares if you wish.
www.ecoindustries.co.uk
020 8961 0599
Mark
October 2009
Aha - piston ring and cylinder barrel then, unless you have a burnt out valve - which can be seen with the cylinder head off. I don't know about spares availability for these - but a motorbike repair shop could advise you as to a rebore and new oversize piston, if possible.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix motorcycles.