Modifications - Performance Discuss aftermarket and DIY performance modifications

One silencer or two?

Old 06-14-2011, 09:02 AM
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One silencer or two?

Is anyone already tried this?
I do not own a VTR but a 2002 XLV 1000 Varadero.
Same engine(somehow)different frame,wheels etc.
I am on the way to modify my bike,with a 1997 VTR engine,front/rear VTR wheels and later an usd fork from CBR.
The matter is both Varadero and VTR as well are using two silencers,god knows how heavy they are.
What about if i install only one silencer?
Do you think i might have any future problems,or bad engine operation because of this?
My goal is to loose some kilos
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Old 06-14-2011, 09:26 AM
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You can go with just one, (it has been done) but it should be an aftermarket slip on, or one off a bike designed for only 1 at around the same displacement. (1000cc)

Because a single stock unmodified silencer has a small outlet and could choke the bike.

Just going to aftermarket can save a lot of weight. (aluminum vs steel)
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Old 06-14-2011, 09:49 AM
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If you go for one exhaust then be prepared to lose approx 15bhp and to have a change of tune (tractability)
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Old 06-14-2011, 10:20 AM
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To begin with, the two engines are very close to each other but the Varadero has a slightly higher stock compression ratio (9.8 vs 9.4) and smaller venturis. Not sure if the ports and valves are smaller but I would tend to think slightly so (given that it was tuned for improved low-end power).

As for a 2-1, I ran one for two years, I can attest that it is doable (I cut the header just past the start of the collector and fit a single Blue Flame can and link pipe originally designed for a 98 R1). The bike ran fairly well. My dyno verified numbers indicate a slight drop in peak torque with peak hp staying about the same. The main difference was a dip in the torque curve between 4800-6500 rpm (at least with the set-up I ran).

Can it be done? Yes. Do I recommend it? It`s all about where your priorities are.....
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Old 08-03-2011, 03:55 PM
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I know this hasnt been discussed in a while but ive been thinking about running a single shorty/gp style of my own design however on top of that Im planning on going with high comp pistons/connecting rods, head porting and valve job,cam regrind, lightened flywheel, velocity stacks, and a few other mods this winter.

My question to you Mikstr (or anyone else) is what was the setup you ran with the single can and do you think with tuning, running a single can such as a shorty/gp to open up the exhaust be beneficial to the setup I want to run?

with my own design shorty/gp I will design it so I can either swap out inserts for different back pressure or make it adjustable back pressure
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Old 08-03-2011, 04:04 PM
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Yeah, so I am pretty sure you wont lose 15hp. That is just a made up number. For example, the end of days is next Friday.

As for doing a single exhaust, I have covered this in other posts but will say it again. It is a lot of work and requires someone skilled in many aspects of engine design, fabrication, and continual repair and modification. You will end up doing R&D for a long time. I didnt go with a single, but I wish I hadnt made my own.
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Old 08-03-2011, 06:21 PM
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well in response to that Im sorry for not doing my research regarding peoples success in jetting for the dr honda velocity stacks but arent they equal length and longer then the longest stock one?

how does this balance the engine, and I feel as though having longer equal length velocity stacks and a single exhaust with the headers meeting eachother at equal lengths would lead to front to back cylinder jetting close to equal..

am I correct in assuming this or is there something Im missing?
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Old 08-03-2011, 06:38 PM
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Originally Posted by scottiemann View Post
well in response to that Im sorry for not doing my research regarding peoples success in jetting for the dr honda velocity stacks but aren't they equal length and longer then the longest stock one?

how does this balance the engine, and I feel as though having longer equal length velocity stacks and a single exhaust with the headers meeting each other at equal lengths would lead to front to back cylinder jetting close to equal..

am I correct in assuming this or is there something Im missing?
Well you are missing the point that the jetting is staggered not because of the stacks or exhaust but instead is set up that way due to the fact that the rear cylinder runs hotter than the front. This is because the front cylinder also receives air cooling and it does make a big difference.

Last edited by 8541Hawk; 08-03-2011 at 07:57 PM.
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Old 08-03-2011, 07:12 PM
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well there we go... thank you for that 8541hawk... it always made me wonder why the jetting was different...

now i got some things to think about...
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Old 08-03-2011, 07:13 PM
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Originally Posted by autoteach View Post
That is just a made up number.
Actually I googled it and 15 is a real number. It comes right after the number 14 and just before 16.
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Old 08-03-2011, 07:41 PM
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Fine, show some dyno charts. That should be sufficient.
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Old 08-03-2011, 07:53 PM
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huh...
I don't have any dyno charts, but I did have a yardstick in the closet. I looked closely, and I'll be damned, pwshadow is right
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Old 08-03-2011, 08:01 PM
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Well, start praying then.
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Old 08-03-2011, 08:19 PM
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Well this UK VTR's owner was sorely disappointed in the performance after crafting & styling his 2-1 exhaust and was going to revert back to 2-2. "15 bhp loss " were his words...

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Old 08-03-2011, 08:55 PM
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I suppose that had I built a 2-1 exhaust and done no design research or tuning that it would hurt the numbers. In its worst form mine put 103hp on the dyno. I would say that if someone is putting 118 down with a bone stock dual exhaust vtr, damn I am an idiot. Now I know that I should have left it alone.

And, by the way, my research tells me that shouldnt be the only disappointing thing about his set up The exhaust hitting the tire should be another (unless he shimmed his rear up substantially).
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Old 08-03-2011, 10:22 PM
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Originally Posted by Wicky View Post
If you go for one exhaust then be prepared to lose approx 15bhp and to have a change of tune (tractability)

If not done uncorrectly, you could lose a lot more than 15. If done properly, you won't lose anything, and may gain some. They do make a single exhaust setup for the RC51. No reason it wouldn't work on the bikes older brother.
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Old 08-04-2011, 03:39 AM
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Originally Posted by Stevebis1 View Post
huh...
I don't have any dyno charts, but I did have a yardstick in the closet. I looked closely, and I'll be damned, pwshadow is right
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Old 08-14-2011, 08:46 PM
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Hey everyone...my first post on this forum.

Just bought an 04 that was a salvage off a local guy. My 04 has a 2-1 with a Muzzy can. Since I was not the original owner I don't have much to compare the power to. I just thought this was a normal mod.Name:  IMAG0118.jpg
Views: 17
Size:  176.3 KB

Last edited by raceruss2003; 08-14-2011 at 08:48 PM.
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Old 08-15-2011, 12:03 AM
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Nope , most v twin bikes work - perform better with two silencers,cans , whatever you wanna call them.It has to do with the volume and the pulses that v2 engine generates.Even if the single can has the volume of the twins , it won"t be the same.
Back in 04 when edwards was racing with rc51, they had it with twin cans.
I bet they had the technology to use one if they wanted.
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Old 08-21-2011, 06:34 PM
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I bought a 2-1 setup from Nemish a while back. It has a Mori Ti cann, but the inlet is stock size. It dyno'd around 101, but made tons of torque. I'm not sure how much testing he'd done, but it was nearly 15lbs. lighter than stock. Maybe that's the "15" they're talking about?
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Old 08-21-2011, 07:43 PM
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I will agree that 2 into 1 will cost power (and rideability) on any twin. You can save huge weight with carbon fiber cans and titanium pipes and keep the tune. It is hard to have 2 different lenth exhaust tracks and get a well tuned balance imho. Just my vote
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Old 08-22-2011, 02:35 PM
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here is my 2 into 1, it works great, seat of the pants dyno says lowend and midrange torque is better, could be the weight reduction too, no dyno data, so its inconclusive, but i had to do it this way for the SSS conversion.

only performance data i have is from drag racing my friends 916, i can stay even with him until 100mph then he starts to pull away about a bike length or two, same as it was with gutted stock pipes.

that is a TBR C3 can. i have to repack it every 10k or so. other than that it works very well. i'm using stock air cleaner, stock jets, needles shimmed up 1mm, screws out to 3 turns.

VFR owners ask me all the time how i got my VFR to sound thataway, i say i cut off half the engine then bored out what was left to the water jacket...can you believe that sh*t, a vfr owner can't recognize that is not a vfr?
Attached Thumbnails One silencer or two?-sse.jpg   One silencer or two?-sse1.jpg  

Last edited by chp_hates_me; 08-22-2011 at 03:39 PM.
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Old 08-22-2011, 05:58 PM
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Hey, hater, can you pm me some pics of the linkage on your swingarm setup? I am rebuilding mine & just wanted some reference. Bike looks great.
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Old 08-23-2011, 07:15 AM
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here ya go smokin joe

here are some pics. if you need actual dimensions i may be able to find them somewhere on my backup drive, (it was many years and 25k miles ago i did the SSS conversion), so you can give that geo to a machine shop and they can make you a dogbone. at my previous job we had a machine lab, i was able to make all these parts for free, with some help from our model makers. i have a lathe and mill at home, but could never make this dogbone, that would require a wire EDM.

you can see some of the EDM work in the pic. but after the burn i had to fixture the part and use a boring head and a mill to machine the pockets for the bearings and seals. i also did a MES (mechanical event simulation) to calculate the required length of the dogbone so the shock wouldn't know that anything changed, since the vfr SSS is 25 mm longer and the linkage attachment is also 25 mm further back. so in a nutshell the shock is doing the same amount of work as with the OE swingarm...force*displacement.
Attached Thumbnails One silencer or two?-linkage1.jpg   One silencer or two?-linkage2.jpg   One silencer or two?-linkage3.jpg  
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Old 09-18-2011, 12:14 AM
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I mailed to Akrapovic about this matter and they answer by this.


Dear mr. G........

Slip-on systems are allways designed acording to original exhaust pipes. If you want single muffler you need to redesign complete exhaust because only one original outlet from mid-box is too small for single muffler concept.

Thank you for your question,

Best regards,
Akrapovič d.d.
R&D department
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Old 09-18-2011, 07:46 AM
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That makes sense & is what I have heard from my mechanic race tuner buddy. He just redid my 2intoOne devil on my bike. Previously the rear header was way shorter and more convoluted. I always had jetting issues on low end. I will post some pics when I get the bike back. He also rebuilt my single sided swingarm linkage out of solid stock.
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Old 09-18-2011, 10:10 AM
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I'll just throw this in, I'm just getting started on my first VTR1000 but I have owned a CBR1100xx Blackbird for a few years now. When I got it, it only had one Yoshi muffler and I honestly didn't think too much about it. Then a couple of years later on a very high speed section of a ride with a few other bikes, my bike ran so well that it got everybody talking that evening. I was somewhat embarrassed when somebody took a closer look at my bike and then asked me if I realized that I wasn't just running a slip-on but a full Yoshi system.

To make a long story short, I got to researching this and it turns out that keeping the inertia of that single column of exhaust gas as unhampered as possible was actually easier with a single muffler.

So I don't know about the SuperHawk, but the same may hold true.
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Old 09-18-2011, 10:18 AM
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Originally Posted by manosamos View Post
I mailed to Akrapovic about this matter and they answer by this.


Dear mr. G........

Slip-on systems are allways designed acording to original exhaust pipes. If you want single muffler you need to redesign complete exhaust because only one original outlet from mid-box is too small for single muffler concept.
I don't necessarily think this answer holds true for all bikes. I can see how this would be true doe my Hayabusa where all the exhaust gases from the 4 cylinders are collected in one chamber and then there are 2 outlets from that. On the Superhawk there is no collector box and everything definitely flows through a single tube for an inch or two before it splits to the 2 mufflers.

PS. You wouldn't fool this VFR owner chp_hates_me

Last edited by dehning; 09-18-2011 at 10:24 AM.
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