Hi Hermit , I am sure that you can overbore the cylinders , that rg150 , if it has the same size gudgeon pin as us then we can make a plan !

That piston is 61mm ? I wonder if they have 2mm oversize ? The powervales would need to be cut back and some porting done . I think it can be done .

I have 2 scrap barrels now that will make a good donor towards that project !
80 + HORESPOWER HERE WE COME !

Now that's a second a lap