|
There is no advantage in having exhaust primaries so large that they out-flow the exhaust valve(s) - because in reality they won't. Rather than sizing the primaries to exhaust port size, I size them to match exhaust valve area. So, for example, for a single exhaust valve 1.25" diameter, 1.25" bore will be fine. For two 25.4mm exhaust valves, 36mm bore would be fine.
|