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Searched for this specific question no luck.... Looking for some feedback/experience with jetting changes after a similar engine rebuild to mine. I am getting close to assembling my 1216 rebuild and I want to have the jetting as close as possible to 'acceptable' for the initial start-up and break-in, especially for that first half-hour of run-time. I've done some reading on the affects of increased displacement, increased head-flow, and increased compression ratio and all three indicate a decrease in richness, which I admit, was opposite to what I would have guessed. So smaller main jet and leaner needle position are likely needed. Rather than specific jet sizes, or needle position, which is going to be individual based on exact engine specifics and altitude, and other variables, etc. I'm hoping to hear some feedback on just how much of a change I should be looking for. ie 1-2-3-4 jet sizes smaller? I realize I will have to go through the usual steps of dialing in the jetting as I normally do. IE full throttle runs to find best main-jet, followed by needle-jet clip position, float height etc. But just wondering if anyone has any first hand examples of how many main jet sizes they had to change, or how many clip positions etc, with a similar engine rebuild as mine. I have BST38SS carbs nicely set up before the rebuild. I have the Factory Pro 38 mikuni jet kit installed. Think I have a 152.5 main, and needle at top(leanest), or possibly second from top clip position. I live at 1100 meter altitude which leans things out too. The following are the engine changes: -1216 JE kit -11:1 -Head ported by experienced oil cooled head porter -30/26 valves -stock cams Any experiences or feedback is much appreciated!

Does anyone know if a stock 81mm SV650 piston would work in a 1216? I was curious if it might give more compression than a stock Hayabusa piston. Pin height seems to be different and the dish seems less pronounced.