2 into 1 exhaust

[Darren69]

[Kinda my thoughts too 1 big dustbin sized can vs 2 smaller ones weoght saving will be negligable unless they're standard oem cans which are very heavy, 2 small carbon race cans very light and easy to source.

[utopia]

Originally Posted by Kato

Biggest mistake people make is thinking bigger the bore the better

Just for the record, I wouldn't have chosen the bigger bore (50mm) headers of my system.
But the rest of the system was exactly what I wanted so I put up with the bigger bore.
Mind you, although I cringe slightly at my shallowness here, I have to admit that the 50mm headers do look cool.


Also, on the silencing capabilities of one can vs two, I said this ....

Originally Posted by utopia

On the downside, where one can is doing all of the silencing for the entire system (remember that each cylinder exhausts through both silencers simultaneously in the std system), I imagine its harder to keep the noise level down. That has been my experience anyway, albeit fairly limited.

Coupled with its short..ish, straight through carbon can and a homemade db killer, I struggle to keep it quiet.

And yes, its true that my system is not the quietest but its certainly not twice as loud as a two can system. Far from it.
My earlier comment may have given an overstated impression.

On weight comparison, my previous system was std headers with high level link pipes to a pair of DP titanium straight-through cans.
Weight comparisons are as follows ...

std headers = 2.52kg
DP titanium can plus high level link pipe 2,41kg x2
Total = 7.34kg

Sil Moto system
Complete pipework inc high level link pipe = 2.12kg
Carbon can = 1.14kg
Total = 3.26 kg

As you can see there is a considerable weight saving of over 4kg, even compared to a system using twin, super-lightweight cans.
Mind you, direct comparisons are always tricky and I should point out that although the Sil Moto headers use bigger bore pipe, they are much thinner wall and as the above figures show, slightly lighter than the std, small bore headers.

Although I do value the weight saving (its hard to shake off Capo's influence) but for me, the simplicity of the single can system, both visually and mechanically, is the overall deciding factor.
On the other hand, those who's personal preference is for twin-can symmetry may disagree.

[900Rebuilder]

Utopia it would be interesting to know what Silmotor system you have as my headers which have the cross over pipes are only around 45mm from memory but are very light compared to the stock pipes. I've got some unbranded 2/3 length oval carbon cans for my bike so the system is much lighter than original and potentially will be quite loud. My purchasing was led totally by the look I wanted to maintain with a secondary nod to sound and performance.

[Darren69]

45 mm headers is ok 50mm over specced esp for a 750 but Ducati messed with 70mm headers on the 999/1098 to reduce noise I think, i can't think of any other reason for it.c

[utopia]

I bought my Sil-Moto system secondhand so I don't know exactly what it is.
I've only ever seen one other like it.
It came from America and had clearly been crashed as it was quite damaged when I got it.
It was cheap though and the basic design was almost exactly what I was after so I took a punt on being able to repair it.
It needed a section cutting out and replacing from the front header which was seriously scraped and half flattened.
I would have had to cut the front header to shorten it to fit the 750 anyway, so it wasn't so bad.
And yes, the headers are overkill (probably) at 50mm bore although I didn't realise this at time of purchase. And the whole thing is 1mm wall thickness (I think the std headers on my 750 were 1.5mm wall) and its extremely light..
The tube is actually the same size spec as the std hi-level link pipes from an S4R. I know this because the replacement section that I used was taken from a link pipe given to me by Capo which came from the original system on his bike.
I measured the length of the headers and was pleased to find that they are both the same length.

I don't do photos much but there's a pic on post #4 on this thread from the 2019 weekender.
http://ukmonster.co.uk/monster/showthread.php?t=57395

I didn't notice any particular gain or loss in performance after fitting the Sil system but I must admit that I did nothing to tweek the fuelling so I may not be getting the best from it.
In my defence this was because I had a pair of Kehin flatslides to go on and I was waiting until they were fitted before heading to a dyno.
Then covid and life got in the way and the Kehins are still waiting (yes I know ... shame on me).
But it does seem to run ok as it is.

[Bitza]

Just came across an interesting fact(?), crossover pipes on twin exhausts are apparently very effective in reducing db's.

[Darren69]

My 50mm full Termi would disagree but there's nice loud and nasty loud. My neighbour came out one time, didn't complain about the noise, just said you're shaking my windows!

[900Rebuilder]

Originally Posted by Darren69

My 50mm full Termi would disagree but there's nice loud and nasty loud. My neighbour came out one time, didn't complain about the noise, just said you're shaking my windows!

Neighbour poked his head over the fence when I first moved into my house and fired up my old 996 - cor that sounds bloody lovely was his response much to the chagrin of my ex who hated the open pipes