Originally Posted by RallyBob
I am considering the 2-ring setup for Bonneville. I'm not concerned with longevity since I only need to run a few 5 mile passes. But it should not be an issue regardless, current Moto GP and F1 engine design practice is to use 2-rings. However with a low rod ratio the piston rock *may* be an issue for ring seal. Remember I will have a 2.21:1 rod ratio, so the side loading on the piston skirts will be greatly reduced. I'm not sure of the effect on a long stroke engine with a 1.6:1 rod ratio.
Pin buttons are a 'crutch' so to speak, but they have been used for many years in various forms of racing successfully.
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so I'm back to square 1 with the rod ratio problem...
combining the various rods I have & crank offsets I can make,
assuming a reasonable piston cd with a 97mm bore,
the displacement vs rod ratio combo goes this way:
2512cc (85mm stroke) R = 1.63
2409cc (81.5mm stroke) R = 1.70
2383cc (80.6mm stroke) R = 1.74
2291cc (77.5mm stroke) R = 1.78
2512cc is a variation with the std 2.4 crank,
2291cc is the easy to build "long rod 2.3" ,
now what a mess (and money...) to build the 2409cc & 2383cc versions,
these are just about 100cc more than the "long rod 2.3"!
Hiro