Hi guys !
It's been a long time I haven't post in your forum. One more time : HI ! :)
I'm actually making a double exhaust for my modified GS. It's a " cafe racer " now. I have a pair of a Norton like exhaust. ( Sorry if my english is bad )
I'm wondering how to make it for having best torque and perhaps best power. On the OEM, there's one pipe at approximately 1 foot from the head. I guess it is not really necessary, just for reducing sound. It is what I read in technical reviews. Ninja 500 and european Honda CB500 twin don't have it. The second pipe between the two main pipes is about 70-80cm ( ~ 25 inchs ) from the head. I think it is necessary to have it for exhaust accordance, and good power. But I'm not sure if it is necessary. I try to have best torque, it is a road bike, with non modified cams but improved head ( porting, head milled, 36mm carbs and 5 degrees ). What are you thinking about ?
Just for fun, a highly modified GS with double exhaust on a dyno, it is awesome ! http://www.youtube.com/watch?v=11Mike0d-lk
Mine is like that. There are just 2-3 more stuffs since this pic :
(http://i39.tinypic.com/15ob3mw.jpg)
As I'm here to speak, I would like to say hello to former forumers like Srinath or Bob Broussard if they are already there. Last year I worked in Quebec and spent 1 month in United States, doing a big trip from Quebec to Vancouver in a minivan. I was in New York, Niagara falls, Chicago, Saint Louis, Memphis, New Orleans, Dallas, Colorado Springs, Las Vegas, Salt Lake City, Yellowstone and Seattle. I met great and cool american peoples. I want to come back now and work for a year, if I can. I'll have to improve my english, before. :thumb:
Regards
Hey man, that's a great looking bike. I'd love to see some more pictures. What kind of exhaust is that? If I'm thinking of the right part, it's a pipe that runs between the headers to equalize the pressure.
Very clean, and I love the shiny engine cover!
If you want performance, your best bet is probably going to be a single exhaust. A 2nd muffler adds a lot of weight, and I highly doubt it's going to give you any real power advantage.
Holy hell that is a nice cafe/GS!!! More pics please!!!
I too am in the mindset to try a dual exhaust. Been reading a lot here and there and it seems that a GS is not a good platform to do so.
Details on the seat pan, please.
Didja make it yourself, or modify it from something that fits something else?
How's the foam for daily riding, and is there a pinch-point where it meets the tank?
I have heard this story of this guy who's 300 lbs and to "make his bike faster" he put titanium bolts on it everywhere. Cost him like 1500 bucks.
Yea very smart ... a dual can is the same way. A lot of work and $$$ for what I would definetly classify as minimal gain.
Cool.
Buddha.
I can say that I had been riding my bike with only a straight pipe. This past Friday, I went to a muffler shop and had a small mid pipe welded to the straight pipe (header) and installed the D&D exhaust I had been waiting on installing. I believe the bike has been more responsive with the muffler on than without. I am not sure if that goes the same for running each cylinder separate but if it is anything like running without a muffler, it might "feel" like the bike performs worse? Just my thoughts.
PS. MORE PICS, MORE PICS, MORE PICS, MORE PICS. The more I see cafe style bikes, the more I likes. O0
I'd be interested in seeing what you came up with, but I also have to throw in my uneducated opinion that a bike as small as the GS wouldn't do as well with 2 exhausts. Engines need a certain amount of back pressure, and most modern pipes are just going to be too big to do that. Most bikes you see with dual pipes all have large motors, usually 1000cc or more. I feel like the double exhaust would be like cboling said his bike felt with only the header.
There are smaller bikes that have dual exhausts though, so if you find the right kind I think you'd be fine, and it could come out looking alright. Ninja250s have dual exhausts, so obviously it can be done on smaller engines, but just definitely make sure you find the right exhausts if you're going to go through with it.
I like your tail.
(http://i160.photobucket.com/albums/t196/84CrapJ7/1270583189685.png)
HAHA! That smiley reminds me of Wren and Stimpy!
That smiley reminds me of the guy that put Ti bolts on his bike.
I have heard hayabusa fools wonder out loud why they dont have chrome bolts in titanium.
The cut off header vs pipe is a valid one, it will run better with a proper muffler. It needs that muffler to provide it a scavenge effect. The separate pipes also is in theory valid, it sorta does a self scavenge and does so without intervention from the other cyl. However it has a resonance freq, like a certain rpm where it works right and every where else its not as good and in a different rpm range its down right negative. if you design the pipe right you can get such negative locations out where you wont be much, and the positive where you will. Say you need 7-8K for highway runs. You need 2-3K for town and take offs. You can build it with that in mind. Will get you a whole tenth of a horsie ... yea ... 1/10 ...
Lots of work and little gain. OK fine a whole horsie. Prolly not, a dry clutch barely gave em 2 for the GSXR 750 limited edition in 1986.
Cool.
Buddha.
Yeah, I heard that those titanium bolts didn't help that much, but then he filled his handlebars with helium and WOW!!!
Since you didn't deliver on the tail, I now side with the other guys.
(http://i160.photobucket.com/albums/t196/84CrapJ7/the-need-for-speed-fat-fail-owned-m.jpg)
They make leathers that big.?!?!?!?!? Wonder how many cows had to die for that suit?
Nice bike btw!
Mary
more pics!!
Hi guys !
Last pic is :
(http://i43.tinypic.com/15i7s4k.jpg)
I have the double exhaust done now. But no pics yet.
Don't make me call shenanigans!!!!
Quote from: O.C.D. on May 28, 2010, 03:14:31 PM
Don't make me call shenanigans!!!!
I'd better go get my broom!!
Quote from: Olivieeeer on May 28, 2010, 03:02:44 PM
I have the double exhaust done now. But no pics yet.
hmm.... mail me your old one. It looks way nicer than the V&H I have.
The issue isn't even that guys leathers, but the fact that he still felt the need to slap some knee pucks on there!
Quote from: tt_four on May 28, 2010, 06:22:41 PM
The issue isn't even that guys leathers, but the fact that he still felt the need to slap some knee pucks on there!
maybe he needs them because the bike just tips over when he's turning and it's the only way to keep it from hitting the ground? im no math wiz but im sure there needs to be a lot of forward motion to keep that bike from just dropping straight down in a lean..
Wouldn't a double set of mufflers be easier to get that thundering ducati-termigioni like sound character out of without fitting a oval muffler as big as the bike itself?
I've just hammered out a rather ratty slip on muffler, and it's a bit sharp and farty sounding.. But bigger is not good either.. Perhaps dual is the way after all.
Please up a vid of the resulting sound signature Olivieeeer. Awesome looking bike btw. Makes me wanna attack my bike with grinder and welder, in spite of the original plan to keep it just that and using it as a boring everyday hack to save my turbo ninja some wear..
Cheers
You want more pics ? I have !
(http://i45.tinypic.com/kf4fn5.jpg)
(http://i45.tinypic.com/24zagzc.jpg)
I will take time to make a vid. The sound is .... vintage, and LOUD ! :icon_eek:
if engines needed back pressure, we could all get more HP with potatos or doughnuts stuffed into exhaust tip. I wonder why some people think back pressure is good? Back pressure is evil.
Two mufflers is better than one if it lowers back pressure without being too loud and you rejet appropriately. Except they are heavier than one with piping. And they look good if set up nice.
Anyway, the bike is awesome.
My 1975 Commando 850 (bought 1976) had dual exhaust. It had balance pipe, clumsily and ugly-ily connecting the two sides, towards the front. An upgrade I did not buy was two into one into two. The two into one gives more scavenging power, the one into two gives sound muffling with less back pressure. One larger low back pressure muffler would work best (most economical with the metal) but this approach is not part of the current motorcycle world.
I think mufflers are the same as airboxes in this regard. You cant have too big an airbox, as long as it fits.
The bike looks awesome with those new exhausts, they definitely fit it well!
Quote from: johnny ro on June 04, 2010, 03:53:31 AM
if engines needed back pressure, we could all get more HP with potatos or doughnuts stuffed into exhaust tip. I wonder why some people think back pressure is good? Back pressure is evil.
Unfortunately it's a bit more complicated than that. There's too much and too little back pressure, and you need to get in the right spot. Aside from the exhaust there's other random things you don't think of like valve overlap, some higher hp bikes use more to suck some of the old air back in with the fresh air before blowing it back into the engine, as opposed to having less valve overlap on the same motor to give you better low end by blowing less air back. Having certain amounts of back pressure in exhausts can also help to mix and suck the air/fuel mixture into the motor more efficiently. There's definitely a good chance there's some errors in how I worded that, because I don't know a ton about engines, but I definitely know there's a few things going on more complicated than air/gas in and air/gas out.
Actually my exhaust is a direct 2 into 2. Works good, and particularly loud. My choice is to remove the pipe front of the cylinders, and put it under the engine and have a more common 2 into 1 into 2, like a EX500.
For sound, I will make some reducers.
wow that looks fantastic!!
You do have that connecting pipe right by where the header bolts to the engine, so even though it's not really 2-1-2, the pipes at least get somewhat of a chance to equalize.
I'm really liking the TRX too, it's a great looking bike. For some reason I always thought those were v-twins, but obviously they're not.
theres a ton of information on that http://gs500e.free.fr site, if only i could read french
sweet site
I had those seemless peashooters on my KZ400 and they have an AWESOME sound, I bet the GS sounds amazing with them. Can't wait for a vid clip!
Aaron, try this : http://translate.google.com/translate?hl=fr&sl=fr&tl=en&u=http%3A%2F%2Fgs500e.free.fr%2F
ttfour : TRX is a 270° parallel twin. Ignition is like a 90° V twin. Sound is same, big torque and low power, like 900SS Ducati. Mine is upgraded with 900TDM cylinders, pistons, crank and rods. Cylinders are aluminium with nickel/silicium treatment. These engines doesn't exist in US. Mine deliver about 89hp at the rear wheel, 106hp at the crank. It is 82hp stock at the crank. I have a lot of modifications. It's really a nice bike ! If one of you come into France, I would be happy to accomodate you and try my bikes ! :thumb:
I also have a XTZ750 Super Ténéré, the engine is the basis of the TRX, but it is a 360° engine. It is not as fun as TRX.
If back pressure is needed so badly why aren't race cars built with mufflers instead of open headers or straight through exhaust?
Quote from: Chanse on June 04, 2010, 07:54:34 PM
If back pressure is needed so badly why aren't race cars built with mufflers instead of open headers or straight through exhaust?
Because race cars/bikes run at high rpm constantly so they are willing to sacrifice the lower rpm drivabilty that a traditional exhaust would provide to get more high rpm power. And just to clarify its not necessarily back pressure thats needed, its exhaust velocity. a small amount of back pressure can increase low rpm velocity giving more low rpm torque. but in a perfect engine there would never be any restriction in the exhaust, the pipes would be the correct shape/size/length to provide velocity without restriction. changing the pipe diameter, length, shape, and/or restriction will change the rpm that a particular exhaust will be the most efficient on a particular engine.