if you look at the picture of the pistons in this link http://www.bonnevilleamerica.com/forums/...rt=all&vc=1the Wiseco 10.5:1 is on the left and the OEM 9.6 is on the right. Just eyeballing them shows the same open dome. I measured these up at one time and the center volume of the wiseco was larger than the OEM. the wrist pin to deck was slightly larger but only a few thousands of an inch. I have compression numbers but only for the 12:1. If somebody with a wiseco 904 and someone with a stock motor would do a compression check submit their compression figures, that migt resolve this.
05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter
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