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Vance and Hines exhaust

  • Thread starter Thread starter justkrugerud
  • Start date Start date
J

justkrugerud

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I have an open Vance and Hines exhaust system on my '79 GS1000e, I've been told by a couple of people that an open exhaust system does not go well with older engines because having no back pressure from exhaust is hard on the seals. Is there any merit to this? Attached is a photo of my exhaust
 

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The whole picture is flipped. Note the brake rotor and sprocket. That bike is gorgeous.
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Hearing loss is cumulative, non-curable, so I reco a muffler insert if for nothing other than the sake of your own hearing,
let alone your neighbors and general public in the areas you ride.

My neighborhood is on the other side of a valley where kids ride used to dirt bikes. Could faintly hear them, but nobody minded until someone started riding an extremely loud atv. Neighbors drowned the police with complaints, and result is nobody can ride there anymore.
 
I agree, that is something I am adding this summer, by the time I get to work I've got a headache - I get a lot of complements on how it sounds but they don't have to hear it every day

XR750 said:
Hearing loss is cumulative, non-curable, so I reco a muffler insert if for nothing other than the sake of your own hearing,
let alone your neighbors and general public in the areas you ride.

My neighborhood is on the other side of a valley where kids ride used to dirt bikes. Could faintly hear them, but nobody minded until someone started riding an extremely loud atv. Neighbors drowned the police with complaints, and result is nobody can ride there anymore.
Click to expand...
 
I've never heard anything about "seals".. Which seals are you referring to? It has been published by Mikuni (for sure) that open exhausts are next to impossible to tune.. This basically means that at SOME throttle position you wont be getting the right fuel. For instance, you'll be running bigger mains to accommodate WOT. So at some point between 1/2 to WOT throttle will be harder to dial in correctly because chances are you'll be running rich due to the larger mains.. You can position your needles to help curve this problem but there is only so much adjustability in a set of carbs. That's my take on things anyways.. I know it's harder to tune electronically due to the rate at which the exhaust gasses flow past the O2 sensor. It makes it difficult to get an accurate read on emissions.
On another note I run the same exhaust on my 1100. I've removed the stock "swirl" baffle tube and replaced it with typical 1.5" straight baffle. I believe it will have better flow and still give me the back pressure I need. If I end up displeased with the result I will probably go up to a 2" baffle and tune accordingly.
 
"Back pressure" is a side-product, not the desired goal.
eek.gif


The whole idea is to control the amount of flow through the exhaust. If you have to restrict it some with a baffle, so be it. Yes, you will increase "back pressure" in the process, but it's the reduced flow, not the increased pressure, that is doing the job.

There are no "seals" that will wear out with an open exhaust, but as mentioned, it WILL wear down on your neighbors rather quickly.

By the way, that particular style of pipe is basically designed for drag racing. It exits out the side so you can lower the bike a bit for better launches. Turning right is a bit of a pain, as you may have noticed. Nealhan mentioned jetting changes at various RPM and throttle positions. That was not a concern when that pipe was designed, as it is only used at full-throttle, high-RPM settings.

.
 
Steve, I can agree with you on the fact that the exhaust was made more geared towards drag racing. In that case, you'd only need to dial in your main jet seeing as how it's only intention is to be ran at WOT (which you mentioned)...

OP, if you want more "streetability", less hearing loss, and happy neighbors I'd recommend picking up a baffle. Or just keep on trucking the way you have it if that's what you prefer... But, as far as seals.. as Steve mentioned you shouldn't have a problem..
 
Yeah,
I've rejetted it twice now and still can't get it to run without dumping a bunch of fuel, a new exhaust is my next big purchase for the bike. Thanks

Steve said:
"Back pressure" is a side-product, not the desired goal.
eek.gif


The whole idea is to control the amount of flow through the exhaust. If you have to restrict it some with a baffle, so be it. Yes, you will increase "back pressure" in the process, but it's the reduced flow, not the increased pressure, that is doing the job.

There are no "seals" that will wear out with an open exhaust, but as mentioned, it WILL wear down on your neighbors rather quickly.

By the way, that particular style of pipe is basically designed for drag racing. It exits out the side so you can lower the bike a bit for better launches. Turning right is a bit of a pain, as you may have noticed. Nealhan mentioned jetting changes at various RPM and throttle positions. That was not a concern when that pipe was designed, as it is only used at full-throttle, high-RPM settings.

.
Click to expand...
 
I Is it possible that a baffle from a V&H street pipe will fit that exhaust. They are not very expensive and would definitely change the jetting problems.
 
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