Today I went to coaster's, a 70 mile round trip on a variety of road types, and really enjoyed riding my Mugello 186. It always starts well, is crisp pulling away and is even pretty good on fuel.
I have put the time in setting it up and getting it to run as I want, and it is now rewarding me with some fun. I held it at WOT for several miles on the A11, without fear of any dire consequences.
So I'm thinking maybe I should just stick with what I have and know really well, rather than start all over again and not actually get much better performance... a bit more torque maybe, but it's not like I ride two-up much... And spend my time and money on my current ride and engine; playing with the gearing a bit, upgrade the electronics maybe, there's always something that'll need attention.
It's not even like I have another bike to put it in, so the small block would just sit unloved in the corner, which would be a shame.
On the other hand I do like building engines ...

Anybody changed engines in a similar way, and either regretted it, or couldn't ever go back to the smaller cc ?