I live in the UK and have a CBR150 that has been fitted with a smaller piston and barrel so that it is now 125cc and therefore legal here. I bought it new in 2005 and didn't realise that it was a modified CBR150 as the dealer didn't mention it at the time! The importer has gone bust. It appears that this is how it was imported.
My problem is that I need a new piston and I don't know where to get it from. The UK spec CBR125 only has 2 valves so that doesn't fit. I have no idea what engine the piston fitted to this bike originally came from. The piston size is 58mm x 37.5mm and the piston pin is 15mm diameter. Obviously also it has cut-outs for 4 valves. The piston stroke is 47.2mm.
If anyone has any ideas , I would be most grateful.