On 07/20/2017 12:13 PM, Mad Roger wrote:
For example, why not just get rid of the pipes altogether?
Then you'd have the least resistance (although no tuning) of the air
outflow from the engine.

I guess the argument is that would be too loud (but some pipes I hear
riding past my house, which is on a busy street, seem *that* loud!).

And you probably wouldn't have much scavenging of the cylinder either.
Best case you have a very low pressure node at the right place in the
exhaust plumbing. The problem with that is it tends toward a narrow
power band, hence the two strokes 'coming on to the pipe'.

We won't even go into rejetting the carb for older bikes or
reprogramming the profile for FI bikes now that you've changed the flow
characteristics.