Originally Posted by Hiro
yes I had this valve notch/ring groove issue when I asked this set of custom pistons to JE,
I had to reduce a tad the notch deepth & diameter to be on the safe side.
IMO it's a pity the Total Seal pack is so tall,
if I could use Wossner rings instead this would allow for cd26mm without the need for a oil ring rail...
maybe it's time for me to consider pin button or 2 rings setup,
Bob do you think it's worth trying for my next 2.5?
rod ratio will not be better than 1.60-1.65 in any case.
Hiro
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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.