Finally got some torque out of Mike's 2-1

[DirtyErnie]

Tried out the old 2-1 kit after blowing out a stock headpipe. It still had the stupid mid-range lack of torque with the 18" Cocktail Shaker. A gutted Harley bagger muffler was worse, and sounded like the neighbor's annoying 3-wheeler.
So, I scabbed on a piece of 18" straight pipe, behind the elbow I scabbed onto the collector. There's definitely something to the "pipe length after the collector" thing. Torque was everywhere, just like it should be.

Damned loud, though. Sounded like an apocalypse, even with -30dB ear plugs. I could hear it through the hairs on the back of my neck. What a snarl at 7K...

 

[DirtyErnie]

Now I have to figure out what I want to do next.
I want to build a system that doesn't lose power, but isn't stupid loud. The question is, 2-1 that actually fits the bike and lets me install the crash bar (Mike's doesn't), or a 2-2, with a crossover pipe?
Mufflers are mostly figured out.

 

[Signal]

Nice to hear you had a win.

In the meantime if you want to take the ear splitting crack out of your exhaust cut a slot in the underside of the tail pipe.

The slot needs to be roughly 150mm long and 3mm wide. Start 30 mm from the end of the pipe and work towards the engine.

I don’t know the pulse dynamics of how this works, but it does.

 

[DirtyErnie]

It bleeds off the pressure before the pulse gets to the end. It would also turn the return wave to mush, probably lose some torque somewhere. Pipe needs a square end to have the sudden change in acoustic impedance to send back the strongest negative return wave. Unfortunately, this is also the loudest possible combination.

The slot would act pretty close to the glass-pack I had on there before, still had the big torque hole in the middle RPM. My thought with that muffler was to keep the velocity up for torque reasons, but the wave tuning was more important.
Next mufflers will be "Annular" like what Norton/Triumph used to do.

http://yorkshireferret.blogspot.com/2016/02/geoffrey-roe-annular-discharge-silencer.html?m=1

 

[Grimly]

Next mufflers will be "Annular" like what Norton/Triumph used to do.

http://yorkshireferret.blogspot.com/2016/02/geoffrey-roe-annular-discharge-silencer.html?m=1

Now, that's interesting. I'd never explored annular silencers before, but I'd certainly seen them on those bikes without appreciating what they actually were.

 

[DirtyErnie]

Thinking about making a 2-2 system, 1 3/8" head pipes. Mufflers with 3" x .060" shells and 2.5" innards would have pretty consistent cross-section areas. Would have to re-math if I was going to do a 2-1 based on the Mike's system (except it would actually fit...)

Edit: and re-use the stock crossover pipes. Head pipes would dump into expansion chambers, back as far as the crossover, then the Annular 'torpedo' section. May or may not have a rear chamber, depends on length.