Maybe, but for me the results were conclusive enough to ditch the ever cracking balance pipes.
I believe Norton introduced the balance pipe together with the quieter bean can silencers.
My test was with open peashooters.
baz: the sound changed, but quiter ? .. hard to tell while riding the bike.
Anyway, it is all a long time ago. Still have that pipe lying around somewhere.
If worntorn likes to repeat the test, he can have it..
I have two '73 850 Commando mk one roadsters at the moment. One on balanced headers and one without. One has Emgo peashooters, the other on no-name peashooters. Other than a webcam #12 in the balanced header bike they are identical in terms of anything relating to the exhaust note. The "balanced" bike is definitely quieter, though not by that much, but crucially, to my ears, a much
nicer exhaust note, throughout the rev range. It doesn't lose any of the lovely exhaust note character, just takes the harshness off.
Subjective I know, but everyone who has listened to both, agrees. To give my particular views on exhaust notes some perspective, If you think Harleys with straight through pipes sound good you'd probably disagree with my findings, I think they sound shit, and I ran a 95 rwhp ex racing Harley XR1200 on the road that sounded lovely!
Balanced Commando also noticeably stronger in the mid-range though that could just be the cam? Swapping peashooters makes no difference to results. Webcam would make engine note harsher if anything with it's slightly higher lift and overlap?
This is also my experience with Triumph twins. My unbalanced '68 Bonneville is noticeably harsher (to the point of not sounding that nice imho) than my brother' s balanced '71 Trophy which sounds just lovely. Both identical mufflers and 650 engines (aside from single vs dual carb, a non-event acoustically).
Cracked headers? Copper grease the balance pipe joints and don't tighten one to take out the stress?
Just a noise law mod? Clearly people who say that know more than Doug Hele and his team who fitted them to the Thruxton Bonnevilles in the mid-sixties when noise laws weren't a consideration and track results were everything. Quote from Les Williams on this mod:-
"We also introduced the balance pipe (between the two exhaust pipes) on this bike, again for mid-range power, and it was an immediate success. The silencers were another Hele success. They kept the bike quiet but still allowed good breathing."
