Exhaust Talk - from the MTC thread (moved this as it clutters up the MTC thread)
 

Ooops - not meaning to be negative - Sorry!

Personally I think it's great that MTC have taken the time and trouble to invest in making such a vast array of exhasut options for our beloved Ten'.

From memory the std set up is really heavy, which is why I removed mine and the also overly heavy rear light effort.

Perhaps MTC can add some science here, but I just do not see the need for two pipes other than aesthetic. Yes, the lovely MTC cans are lighter and that is of course good compared to standard.

I tend to change exhausts as a 'must do' on just about every bike I've owned since 1982... and that's a lot of bikes.

I prefer the single can solution from both aesthetic and weight view points and also prefer the RG tail tidy which weighs about a gramme (when compared to standard set up).

Once again - great to see the choice and I hope MTC are able to offer the single can solution too in the future so that all options are covered and keep up the good work.

Cheers.

I don't think you are being negative, I agree with you. The bike comes with a single can system (albeit with two vents) and it is heavy.

I too would like to know the benefits of a dual can system on a bike over a single can system.

I appriciate the difficulties in producing a single can for the Tenere (in that it's a fairly short can)

I would like to see something of the science and engineering that suports the use of two cans over one.

A single can system would certainly be on my shopping list, as long as it was value for money.

Thanks GULG.

Due to me losing all my Ten' pic's when the PC died, I can't recall the exact weights of the original and the single can and I can't be arsed to take it off to weigh it now!

Like you, I'm interested to hear an expert's opinion about gas flow 'n all that. I also fitted Kev's fuel mod and the K&N air filter so other than a PC now, I just have the baffle to take out. Silencing with the standard baffle is more than adequate.

I can recommend the following books if you are interested in learning about exhaust design:
The Scientific Design of Exhaust and Intake Systems (Engineering and Performance)
Four-stroke Performance Tuning Second Edition

Silencing a big single isn't an easy task; the noise frequency is low but penetrating. As the pressure wave moves along the inside of the silencer there are a few different methods of actually providing a reduction in noise. The most common is to have a series of perforated tubes and plates to break up the path of the pressure wave, thus reducing the volume that comes out of the silencer. This is known as a reflective silencer. If you cut open one of these silencers then they will look something like this-

http://www.panteraplace.com/Exhaust/...uffler%20b.jpg

That's a car silencer, but you can clearly see the tubes, plates and volume of space available for the pressure waves to move around in.

What is often referred to as a 'race' or 'straight through' silencer uses the method of absorption through a single perforated tube, wrapped with an absorbing material such as glass mat or wire wool. Like this-

http://image.off-roadweb.com/f/94008...er_cutaway.jpg

They are referred to as 'straight through' as obviously the pressure wave can pass straight through the silencer, without losing as much gas speed as in the normal reflective type of silencer, thus you lose less power.
They are also very easy to make as all they are is a tube, with a perforated tube inside. You can alter the length to provide more or less silencing, and with an increase in length you will get a slight increase in back pressure.
What is more important in exhaust design is the length, bore and shape of the pipe work from the exhaust port to the silencer. The silencer is only really there to silence the machine. The changes you can make to back pressure via how much you choose to baffle or slow down the gas/pressure wave will have an effect upon the performance of the machine, as will how open or short you have the silencer, or whether you fit one at all.
You can make adjustments as well by the inclusion of cones in the exhaust system, in order to reflect the pressure waves back, or allow them to expand.

However; it is very important not to view changes in isolation, if you are wanting to have a less-restrictive silencer with a view to gaining an increase in power from your machine, then you have to anticipate that the gas speed will increase, and thus your combustion chamber will be emptied faster. Without increasing the amount of fuel, and the corresponding amount of air, entering the combustion chamber, you will have a lean mixture which will provide negative results not only in power, but also in engine longevity.
The XT660 engine has a twin port head and as such the gas speed will be higher compared to if the same engine had a single port head. This in turn means that the amount of silencing needed is greater in comparison to a single port as the frequency of the sound waves will be higher.

After experimentation with single and twin silencers of differing lengths, I believe the most efficient and balanced method of silencing the XT660, with positive results in the power stakes is a longer single silencer with an absorption baffle, placed after a shallow reverse cone megaphone.

Hope that is of some use to you?

Thanks Tom,

Very informative.

I'm going to have a guess that the OE can is Reflective, where the MTC (and any other twin pipe setup) is striaght through, hence an inprovement in performence.

But what of a dual verses single can? both would be straight but I imaging there is some loss of performance (by way of gas speed/pressure or silencing ability) by spliting the pipe into two cans...

I'm trying to understand why a dual can setup is the most popular (for the manufactures), over a single can which should be cheaper.

Ok to answer your points in order-

Yes the OE silencer is reflective, and contains the catalytic convertor before the baffling. By doing this, the amount of baffling needed can be reduced, but it isn't a very efficient system for performance.

Which brings us on to the next point; I believe that the majority of aftermarket silencers for the Tenere are designed as twin units to fit in aesthetically with the bike once the neat OE unit is removed. As far as weight, and the removal of it goes, you aren't helping yourself by fitting twin silencers, when one would suffice. However; fitting a single silencer to the Tenere throws up both aesthetic and flow problems of it's own.

If you want the most efficient flow you have the silencer on the left of the bike, but this leaves the right hand side of the bike looking very exposed and unfinished. As the bike leans to the left on the sidestand you get to see the dirty side of the silencer whilst the bike is at rest.
If you decide to fit a single silencer on the right hand side of the bike, then you have to add a couple of bends into the system at the point where the gas speed it at it's slowest, so you risk adding more back pressure to the system. This is also true of systems like the Leo Vince link pipe where there is a smaller diameter secondary pipe going to the RHS silencer. The way this secondary pipe is sprued off from the primary will have an effect on the turbulence of the gas flow at that point, again affecting back pressure. I can only speak of the LV system as I haven't had a look around the others available.
I wasn't too enamoured with the LV system and thought it heavy and certainly the RHS silencer is only there for aesthetic balance.

The OE silencer isn't a dual silencer, but a single silencer with twin outlets. By designing it as such the manufacturer can make use of the space efficiently and stylistically it would tick boxes with their design department.

I think the two cans allow gas flow to be less hindered whilst still providing for a reasonable level of silencing otherwise you end up with the dustbin size silencer thats fitted to the XT1200z. Or its all just styling/asthetics.

I still fancy the idea of making an underseat silencer something like the original SXV/RXVs had. Getting it to actually silence effectively might be a bit hit and miss though :D

Tom

Firstly - Thank You for a superb and detailed reply, much appreciated!

So, you've added some science to what I kind of figured. For me, weight, performance, sound are the important ones as are aesthetics and I opted for the X Racing single pipe, as it's light ally and the baffle makes it tuneable if I so wish regards to noise only. Clearly this is the perforated tube and the link pipe is really quite straight and as such fast flowing with less back pressure. So with this is mind I need more fuel and air, so fitted Kev's fuel mod and the K&N air filter. I have the ARD cases rack +/- panniers depending on what I'm doing, so to 'balance' the rear end aesthetics (I have the R&G taoil tidy there too) is not on my list at all.. I appreciate however other folk may feel differently.

My Ten' is as crisp as it can be (in my opinion and without altering the engine internals) and certainly is a zillion times better than the standard set up. No jittering, lag and quick on and off the throttle response. Not quite like my WR 45O with FMF, but not bad.

There will always be the need for choice, as consumers are fickle and if there's a good single can option from the same twin can supplier, then I think that manufacturer covers all possibilities and maximises their sales potential. Makes good business sense to me and I hope that choice is available soon, as it will probably be much easier than all the bank transfers etc I had to do for my X Racing pipe - worth it though!

Cheers..

I've split this thread off the main one
 

I've moved parts of the MTC thread to here, mainly because it's an interesting thread but not really specific to the MTC ordering proccess.

Carry on....

I don't suppose you'll be coming to the Lakes in May ? I've been wanting to see this pipe, and hear it! for some time. X Racing don't seam to be able to answer questions and I don't know if they have crap Customer Service, or they don't speak/type English well enough to understand me.

What I like about these pipes is you can order the empty can to make up a 'tool-tube' type setup to balance the rear of the bike out a little.

I guess I just want to have a right good poke about at the can and listen to how loud it really is....

Yes - I am definitely there (barring any nasties I'm not expecting). The dates are in my 2011 diary along with another three day jolly down in Southern Spain with Trailblazers.


Poor old bike Ten' sits outside under a cover while a bit of car work has taken over the garage...

Don't forget the baffle can be cut to length, left long or removed completely!

I can remember reading something kev had written and its all about gas flow out, back pressure in the system and noise.

The OE can is restrictive as it has alot of baffling, plates etc in it, this reduces the noise but creates alot of back pressuring meaning the engine can push out the gas or gas flow as much.

Therefore performance cans basically remove all the baffling and put the silencing material to the outer of the can, but its still noiser over an OE, but it has less back pressure, therefore more gas flow.

However, say your using 2 cans, this means you have two outlets for your gas flow, meaning more gas can effectively be pushed it (not just simply 2 times but roughly ball parking there), this is all great and fine at high rpm when getting the gas out of the engine is really what your looking to do. But when you get to lower rpm the gas that comes from the engine going into an exhaust tube which has a smaller back pressure as 2 exhuasts reduces the amount of pressure that can be retained in the exhaust tubes. This means it slightly reduces the pressure in the cylinder for the next stroke not allowing opptimum pressure to be kept.

For a single can, as it only has one outlet less gas can flow through it meaning at higher RPM the bike isnt going to be able to make as much power as a twin can system, but it does however mean that more back pressure is retained in the system at lower revs allowing more torque to be produced.

So really 2 cans means better power in the upper range and bit less torque down low, were as 1 can gives better torque down low but no real up top power gains.

If Adventure Spec made exhaust pipes...
 

Tom has said everything I would have said (even the magazines say the Tenere has twin exhausts when it is clearly a single box, with twin outlets - duh!) - and that the fundamental reason that the aftermarket go with twin pipes is for appearance...

You can see a 'regular' exhaust company like Leo Vince and Akrapovic doing that, but what I don't understand is why the independents don't make a single can (on the left side) and a dummy can on the right that can be used for tools or other storage - particularly as the Tenere has no underseat stowage to speak of?

If anyone has seen Race to Dakar, you'll see they used the 'dummy' offside can on the F650s as a storage container for a water bladder - neat idea.

It wouldn't cost any more to make the dummy can a container, in fact it would be cheaper as there would be no baffle gubbins to go inside - just a locking end cap perhaps?

But what the hell do I know huh?

J x

ps. Uberthumper - if you are serious about an SVX style undertray exhaust, speak to Andy Ainsworth at Zorstec - we discussed the very same idea for my Tenere prior to Heroes-Legend last year, although as you are probably aware, I ended up going for the SR Racing can for convenience and light weight...

I'm pretty sure it was your H-L thread that planted the idea in my head :D

Edit: Oh and I'm not that serious. Or rather I am, but I can think of lots of things further up the priority list for the Ten'.

Hey JMo, UT and I have been speaking on PM as well, and I mentioned the CBR style silencer we had spoken about. He and I have some ideas. My warranty is up in Dec so then I can be a little bit more free with what happens to the Ten.

MTC Exhausts Tenere single can option?
 

Due to the very popular demand from what we are reading we will look at putting a single can version in to production. The boss is very happy with this idea as he's always a fan of a single can as its less weight and most of the time you get more power. All we need now is a bit of feedback, are we thinking left hand can or right hand can? martin said if we get enough interest in this then we will put it in to production straight away. I'm looking forward to hearing from you all very soon.

Regards
paul
MTC Exhausts

Hi Paul -

I'd keep the single can on the left hand side of the bike (makes the most sense and has the straightest run for the link pipe), and offer a second dummy can for the right hand side, for tool/spares/water bladder storage.

I think you'd have a winning combo there for the majority of Adventure riders?

Jenny xx

I agree.

While not everyone would take the option of a tool tube type setup for the right, the option of an 'empty' can is very appealing as the Tenere lacks any sort of storage short of putting bags/boxes on.

It doesn't even need to be a manufactured part, the can case and some blank ends would be enough for most people to produce a storage system.

As for right or left, doesn't really matter to me. I do think it would be more cost effective to have it on the right and you can use the same link pipe specs, so keeping development costs in check.

Single pipe on the nearside to keep in line with the header pipe.

Nice one MTC.

http://www.xt660.com/attachment.php?...9&d=1267132694
http://www.xt660.com/attachment.php?...9&d=1264176016
http://www.xt660.com/attachment.php?...1&d=1264270864
http://www.xt660.com/attachment.php?...2&d=1264270886

From previous posts and for reference really to MTC and others looking at single can solutions for the Ten'. I can provide any pic's that might help - just ask.

Left hand pipe with dummy as an optional extra to keep the costs as low as possible. and keep the clean lines of the bike. With pipe in a couple of length options if possible ie long or stubby.

The major drawback for aftermarket Tenere exhausts has to be the high prices compared to those offered for other bikes.

I realise there are development costs and materials are always increasing in costs but I think the demand is definatly there for a good product at a decent price.

Well done MTC for being forward thinking and delivering the products that people want.

One thing that puts me off so many pipes is the fact that they don't follow the lines of the.bike properly. Most sit at a odd angle (which has been covered on here before). get that right and you'll be on to a winner.

Right on, redbikejohn. Lots of the exhausts I've seen for the XT on here look nasty - and leave great visual holes in the look.
I'm a fan of "sleeper" kit - cans that look OE but are of course lighter and less baffled but have a similar design are nice :D I bet I'm in a group of one though :lol:

i got a OE pipe off ebay and de-cat'ed it two nights ago. aslo drilled a couple of 20mm holes leading to the outside pipes. a bit noisier but not too bad. will post pics soon.

MTC - when is the single can coming? But remember to keep it flat ie follow the old lines. Don't make it like all the others that droop down at the front end.

i was at mtc last week its only two miles away
there is a single can update ready very soon ..a couple of weeks

they have my number and are going to ring me ..

any news on this yet ?

Ta

My MTC can arrived thursday looks great photo soon, cant wait to get it fitted barrrrrrrrrrrrrrrrrp

had a great ride the other day finally got around to fitting my stage 3 filter kit, kev's mod and my mtc.

the exhaust sounds great with the db killer in just enough pop and the bike pulls much better low down, the 3-4k flat spot is gone, 1 of my major gripes with the bike was that flat spot.

the back end looks much slimmer

just need to work on a tail tidy now,

even thought of mounting the number plate under the rear fender so it can be seen past the rear wheel but not sure of the legalities

in a nut shell - well happy well worth the spend

xt600 exhaust on the xt660
 

Has anyone tried fitting an xt600e exhaust system to the xt660? I think motad or micron do stainless front pipes for about �100.