Wiseco makes 86 mm pistons to make a 790 and it is the same setup that PSI and Black Magic sell. It is best used with 44 mm carbs and use early 90's carb ignition. I have one that is ported by Lowell Horning but haven't used it yet. Setup makes 140-150 hp depending on final setup. Pistons come with instructions on how to properly machine heads.
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