Not exactly sure what you mean here but the Homelite C-9, C-91, and C-92 all would have the same stock piston/cyl (i think) you could also use a piston/cyl from a c-7, c-71, and c-72 as I believe the strokes on the 7's and 9's were the same just diffeerent bores. but if you use the 7 stuff your displacment will obviously be lower (85.5cc down to 80.5cc). Hope i answered your question.