Low end on a 125
There was a recent article on the effect of dents and dings on pipe performance. The basic conclusion was that the first few inches of pipe closest to the engine were the most critical in terms of keeping "ding-free." Dents in the expansion chamber yielded no noticeable difference in performance; I'm assuming these are reasonably small dings.
I would be really interested to find a way to add an inch of pipe length right at the cylinder. I'm trying to shift the powerband of my 125 down a few thousand RPM...the power delivery is perfect, but in order to get the woods characterstics I want, I've had to drop a tooth on the front sprocket. It's a bit of a trade-off, because a geared-down 125 has a tendency to spin the rear wheel. The power comes on suddenly, hard, and not always in a way that creates more speed on the trail. Plus, lower gearing reduces the effective time you're in the "meat" of the powerband, necessitating more careful gear selection.
What would you recommend in my quest for the holy grail? Combination of pipe and reed change, porting job, or just leave the small sprocket and shift more often? (Please don't say "buy a KTM 200"; tinkering with bikes is part of the challenge!)
Elf...did you ever experiment with the pipe length on your bike? I think that'd be a really interesting report!