jwenrich wrote on 08/23/16 at 15:58:46:I've been wanting to do the big bore 97mm change for a while now. Came across this post and now I'm wondering; Is there a significant difference between the 97mm High Comp and the 94mm? It would be nice not to have to bore out the cylinder, but how much power would the larger bore get me vs just a higher compression?
More than likely 5%, maybe a little more, that is why I had the 94mm made. The boost in compression is by far the biggest generator of power.
The size difference between the 94mm bore and the 97mm bore is only 42cc in the end, which is maybe 8% of engine volume. Going from 8.5:1 to 10.5:1 CR is a 20% increase in compression. It is not exactly apples to apples but the differences are significant.
And then there are the costs: $575 vs $200-250...almost 3 TIMES more with the big piston.
It's kind of a slam dunk with everything considered.