Does a 2 into 1 exhaust system increase performance

Hi all,
Does a 2 into 1 exhaust increase performance over a twin system? If, so, is at specific rpm ranges?
I believe my T160 benefits from a 3 into 1 but the Norton and Trident engine a very different to each other in their power delivery characteristics.
I guess one advantage of a single exhaust is weight saving and just less physical stuff hanging off the bike but I can’t imagine losing the centre stand off my bike ( I rarely use the side stand.
What purpose does the crossover pipe serve on the standard Commando? I put new headers on my T140V that did not have a crossover pipe (same Dunstal style mufflers) and I’m sure it’s performance picked up considerably. It is louder but I don’t think I’m mistaking decibels for horsepower.
Any thoughts appreciated.
alan

Alan L said:

What purpose does the crossover pipe serve on the standard Commando?

Click to expand...

It's supposed to reduce noise.

Alan L said:

Hi all,
Does a 2 into 1 exhaust increase performance over a twin system? If, so, is at specific rpm ranges?
I believe my T160 benefits from a 3 into 1 but the Norton and Trident engine a very different to each other in their power delivery characteristics.
I guess one advantage of a single exhaust is weight saving and just less physical stuff hanging off the bike but I can’t imagine losing the centre stand off my bike ( I rarely use the side stand.
What purpose does the crossover pipe serve on the standard Commando? I put new headers on my T140V that did not have a crossover pipe (same Dunstal style mufflers) and I’m sure it’s performance picked up considerably. It is louder but I don’t think I’m mistaking decibels for horsepower.
Any thoughts appreciated.
alan

Click to expand...

That’s an impossible question.

A correctly designed 2:1, like the Maney system, can have big benefits on a 360 degree twin, especially in the mid range but also the top end. But it depends heavily on the design of the exhaust as well as things like cams and cam timing etc.

However, I would hazard a guess that the vast majority of 2:1s marketed over the years were detrimental to performance.

Stock Norton headers with stock Norton peashooters actually work rather well on Nortons, which kinda made life hard for after market 2:1 makers !

Ask Al he knows all about 2:1, he knows everything.

Back in 1982 when I converted my 850 Commando to a Featherbed frame I got my new exhaust headers made up for the Featherbed frame from my local exhaust shop that had a mandle bender and a experienced operator, made without the balanced pipe, he made the pipes straight through to the rear where I cut them down to where I wanted my short open mufflers with very little baffles mounted, just enough to keep it quiet but open enough for performance wise.
As Nigel has said it depends on what work is done to the motor, what cam and head work has been done, restricted mufflers will affect performance no matter what system you use, my set up works very well with my cocktail shakers mufflers with very little baffles and have been using similar mufflers since 1982, the quicker my exhaust gases get out the better my Norton performs, but my motor is not stock, built for the Featherbed frame with cam and head work, mine is set up for mid range performance where my power is used the most, but my motor will rev very freely and will rev past 8000 rpm if you let it but I like to keep my motor together in one piece and know when to back off lol, ignition system, carb set up and jetted right as well exhaust system all play a part in performance, get it wrong and could make your bike slower.
My set up work very well for what I use my Norton for and I am using the same set up to this day since 1982 and the same headers that were made back then, been through a few mufflers since.

Ashley

No guarantee of improved performance by just putting a 2 into 1 exhaust on. Actually can have the opposite effect if your tuning skills aren't up to snuff. I've never used a Maney 2 into 1. I doubt he has any for a P11. lol

I replaced a good working shorty dual exhaust that I low sided on and destroyed with a Bub 2 into 1. Getting any kind of pipes in the SF bay area in California for a P11 was difficult for me in the late 1970's, so I had Bub make me one. He was a small operation at the time. The Bub pipe did not like Amals tuned for the dual exhaust very much. No top end but usable low and mid-range if I didn't want to ever ride over 60 mph. I parked it for a decade or more and rode dirt and modern bikes. I got it working in the early 1990's using Mikuni carburetors and a bunch of engine work. My experience is probably not typical for a Commando owner however. I'm still using the 2 into 1, but I made a few changes to it and my engine and carburetion is not standard Norton. No limits on where the engine works in the RPM range as long as I don't lug the engine and ride in the right gear.

The problem with my Mk2 850 is it just keeps going so my actual desire to change anything is low though another few hp would be nice to offset my middle (old) age spread
Best thing I did was put new Premium Amals on it

Are the new Premium Amals set up right for your motor, jetted right, right size piolet jet, needle setting, timing set right etc.