Does anyone know where I can get an oversize piston and ring kit for an RT2. Been looking online and Ebay and dont see any obvious source   regards Terry

Forum members/moderators Enduronut and/or Deet might have what you need. 

For anyone else who is looking for these parts, don't get taken in by sellers saying that the parts fit DT2 and RT2 - THEY DON'T. Look for genuine packaging with the part numbers showing (prefix 308 for the RT2 and RT3).

Question must be asked though--what size oversize. Yamaha go in 10 thou steps four times to get to maximum 81mm. 0.25-0.50-0.75-1.00. Be aware that 10thou only gives 5thou all around "if I'm thinking right" & doesn't take much wear to find one oversize not cleaning up around exhaust port. That's extreme stuff & more applies to abused motors or ones sucking a lot of dirt--not yours I hope.