Originally Posted by
30Tooth
Indeed, the 2058 pops to mind as it has worked well on sirios and nr I have,even SH engines.
Very well put, at this point we need to know what compromises have to be made and still follow rules. If the pipe is good enough maybe even go racing with it just to see how it stacks up. Then baby steps to improve the package.
I think the OS 12 and 28 have less squish bands than 21 engines, at least from the pics. Still trying to spot a pattern.
You've got the old 9886, 9853. Onroad seem to often use the 2015, and both on & offroad uses the 2069, and that's just on top of my head.
Even Novarossi has gone for outside source for a pipe that worked well for other brands, that should tell you something.
New 1/8th off-road tuned pipe - NOVAROSSI WORLD
Different engines do use different size squish area, but it's usually difficult to see exactly how much there is in difference.