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Thanks for feedback all. I have a machine shop that specializes in 2 strokes that will be working on the cylinder. I have also done some more research on the best piston to use. The Wiseco seems to be a copy of the 1978-1979 YZ250 piston. I will be going with one of these depending if it goes 0.5mm over or stays at 0.25mm over since as noted Wiseco only does 0.5mm increments (my previous Wiseco was std bore). Earlier mx or yz pistons only had 1 ring and I want the dual ring for reliability. 1975 mx250 started the larger intake window. DTs kept the dual smaller windows. So the get the dual ring large port combo a Wiseco or a 78-79 YZ250 piston is needed.