OzVMX Forum
Marque Remarks => Yamaha => Topic started by: ola_martin on February 20, 2009, 11:15:11 pm
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I'm planning to make a exhaust for my HL-replica, left side style. I have access to 38 and 50mm stainless tube and bends. 38 is too thin. Is 50 mm too big? What will happen to the powerband if I make one? My engine is a SR with 540 hi-comp.
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in theory you need at least a little back pressure otherwise you will kill the bottom end/mid range and have and engine that is tuned for the drag strip. Bengt probably didn't care about anything except wide open.
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why don't you use one of Geoffs GMC left side pipes, all stainless work of art mmmm mmmm with built in muffler
Aussies dollar is worth nothing these days so good chance
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Yes, I could do that, tried to ask him in a previous post here. Probably better to ask him directly.
If so I need to have it whithout brackets and also I need to cut and weld it a couple of places to make it fit, as I've tilted the engine forward and lower compared to stock a HL.
Just that I've made the rest of the bike, so I kind of wanted to make the exhaust as well. But if I need to specialorder the correct diameter tubes (think HL is about 45mm?) it will be better to buy the GMC exhaust, it sure looks beautiful. Geoffs work is very impressive.
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My limited understanding of fourstroke exhausts is to start with a smaller dia pipe and taper to a large opening to give you the best spread of power.I would suggest asking the same question in the "Tech help" section, none of the clever people bother with us Yamaha lovers down in the cellar ;)
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G`day 38mm is too small and 500mm too big which are 1 1/2 and 2`` you want too use 1 5/8 tube or 1 3/4 i would only use the 1 3/4 if the engine is a hottie .you can use a small a cone in the inlet side to increase back pressure and gas speed. info comes from having made pipes for 15yrs at Tranzac exhausts. if you want more info ring me 3821 6777 robin
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As Robin has said, 1 5/8" or 1 3/4" are the sizes used for most 500 exhaust I have had on my XT, TT and SR500s, depending on the state of tune of the engine.
Having said that, I am currently making a 2" stainless system from scrap SS bend and tube sourced from work for a XT/SR bobber that I am building. The main problem I found with using 2" tubing was that it basically can't be fitted to the std exhaust port stud. To overcome this I have made up the exhaust adoptor pictured below;
(http://i150.photobucket.com/albums/s120/coljay/EXHAUST.jpg)
It has been a fair bit of work and the pipe is going to be faily bulky since the 2" bends are so large, but the pipe is being built for the "look" rather than as a performnce mod, so it isn't a major worry.
CJ
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SR 500 bobbers are big news in Japan.
I have 1 3/4" exhaust for my Daytona head engine, but that is pretty warm
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Thanks guys!
-Shoreline, I don't understand "you can use a small c".
I would have to get up in the middle of the night to call you, and I don't know how my english would be at that time ;) I live on the other side of the world....
Does anyone know of a good place to order bend and tubes on the net? I can only find 1 1/2 and 2" here in Norway.
Would it be a good idea to start small with 1 1/2 then go to 1 5/8 and then 1 3/4. Also on the stock HL exhaust I think the tube is a bit narrower after the muffler?
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The HL pipe won't fit the standard frame but I make a similar pipe to fit the XT / TT frame. The front half is mostly the same, it's the rear section that needs to be different.
Are you using a standard XT frame?
I make my pipes out of 1 3/4" tubing, it's what the original Aberg pipe was & seems to work okay.
I know some guys taper their pipes up to 2' but they are mostly for road racers that want to rev the crap out of them.
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Hi Geoff, good top hear from you.
Do you think the exhaust you fabricate for the XT/TT would be quite enough for registeration or is it more like the HL version.
Carn't wait for the HL Kit to arrive mate.
John (WA)
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quiet enough for registration ;D, what kind of registration as Ii think it would not even get the offroad registration in WA
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Ceramic coated TT500 pipe.
(http://i45.photobucket.com/albums/f65/djracingyz/VMXRnd309Taupo091.jpg)
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-Geoff, I made my own frame from a Husqvarnaframe. I think the frame it self is close enough that the HL-pipe would fit right on, but I've tilted the engine forward compared to the HL, so that it sits more like in a XT. Therefore the angle to the exhaustport will be wrong. Also I need to place the fittingbrackets myself...
There are some pics of my build here: http://www.adrenalintrip.net/hl500-exhaust/forum/viewtopic/60/291295?siteid=1&topictype=0
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Hi marcFX, the question to Geoff related to an XT500 I am currently restoring. However, as long as I have the necessary lights etc on the HL, I can have an engineering certificate completed and then submit it for rego. As the HL will have lights etc ist not that big a task, but the cost would have to be justified. I used to run a YZ465H with full rego on the street. Great "road" bike and easy to get to the favourite tracks.
John
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Hi Ola
My HL pipe may fit your bike, but as you say you would have to fit the mounts yourself, & probably fit the engine spigot too so it's at the right angle.
If your looking for something this side of easter though then I don't think I could help you.
John, the mufflers are the same on both my HL & XT / TT pipes.
Let me know if you want a baffle put in yours if you mthink you might need it a bit quiter
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Thanks Geoff, I'll send you a mail when when I decide on the pipe, want to get a bit further on the bike first.
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Ola,
If you deside to go down the route of making your own pipe, here is a picture of what I have made so far for 2" stainless steel pipe I am making for my bobber.
(http://i150.photobucket.com/albums/s120/coljay/PIPE1.jpg)
Hopefully I will get a chance to TIG weld these sections of pipe fully while I am at work tonight.
CJ
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Hey Ola,
left side exhaust and GMC airbox to give you some ideas
(http://i245.photobucket.com/albums/gg71/marcFX_photo/SANY0248.jpg)
(http://i245.photobucket.com/albums/gg71/marcFX_photo/SANY0345.jpg)
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Thanks Geoff, I'll send you a mail when when I decide on the pipe, want to get a bit further on the bike first.
Hey Ola,
I am undertaking the same project and would appreciate it if you could post or email me more photo's of your frame. Great work!
Sam
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Ola best mod I have seen recently is the HL in the latest Classic Dirtbike, they fit oil inly on top of the motor rather than run the side pipe under the engine. Rest of the bike has some tasty bits as well.
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A friend got hold of a Cheney XT500 recently. It had the oilinlet on top of the engine mod. They had welded the original hole shut and drilled a new one in the same line on top of the case. It saves the oilpipe in case of a chainthrow.
Was it issue 10? I just bought all 9 backissues of CDM, and intend to subscribe from now, so hopefully I'll get it in a while...
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its in issue 10.
these bikes definitely throw chains and the bike in issue 10 has oil line modifications and crazy rock solid chain guard.
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fresh back from the powder coaters
(http://i245.photobucket.com/albums/gg71/marcFX_photo/IMG_1276.jpg)
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Hi marcFX. Do the XT aluminium tanks fit on the frame? I do have the YZ125 tank but also I'm interested in a larger tank?
John
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Hi John,
I am building TT as well (easier to build 2 bikes as a production run) you can see in the photos that the tank of the XT comes back further and thing you will run into the tank mount and front frame loop.
Why not build a TT as well ;D my TT will also be MXer with Simons forks and White brothers swing arm and my big head motor.
(http://i245.photobucket.com/albums/gg71/marcFX_photo/GetAttachment.jpg)
(http://i245.photobucket.com/albums/gg71/marcFX_photo/IMG_1274.jpg)
(http://i245.photobucket.com/albums/gg71/marcFX_photo/IMG_1275.jpg)
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Yea your right. I have a TT frame and enough motor spares. Thanks mate.
John