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Post by Cruizin on Aug 6, 2016 21:16:06 GMT -7
Official Yamaha description "utilizes butterfly valve that prevents the "blow back" phenomenon caused by "valve overlap" " .
Anypne have anymore info on this? They describe it as both a powervalve that reduces flat spots in power but also as a device that reduces emissions.
Anyone have a diagram? I haven't been able to find one yet.
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gord1895
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Post by gord1895 on Aug 18, 2016 20:33:44 GMT -7
From my first impression it seems like an easy way for Yamaha to get the bike quieter in the RPMs they test. I disabled my valve on day 2 and notice no negative characteristics...just better sound all the time. It is pretty easy to temporarily disable or permanently remove.
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danyboy24
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Post by danyboy24 on Aug 19, 2016 8:59:46 GMT -7
How???
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gord1895
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Post by gord1895 on Aug 19, 2016 13:13:56 GMT -7
I started at the EXUP valve where the muffler and catalytic converter join. You remove the three allen screws to remove the shield and under it will be the cam where the EXUP cables attach. You just remove the nut on the top of the cam and remove the spring and dished bottom plate (This will make sense when you are in there) Then I used some safety wire to open the flapper and hold it there so it does not inadvertently shut ever. Then I just disconnected the cables at the servo motor under the seat. I did not remove anything yet since I was not sure how the bike would react but maybe I can pull everything out and get some pictures this weekend since I now know I am keeping it disabled. Leaving the servo motor plugged into the system under the seat will ensure you do not throw a check engine light. Other option is buy a servo buddy or have the EXUP disabled in an ECU flash which is my plan.
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danyboy24
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Post by danyboy24 on Aug 20, 2016 5:55:41 GMT -7
I started at the EXUP valve where the muffler and catalytic converter join. You remove the three allen screws to remove the shield and under it will be the cam where the EXUP cables attach. You just remove the nut on the top of the cam and remove the spring and dished bottom plate (This will make sense when you are in there) Then I used some safety wire to open the flapper and hold it there so it does not inadvertently shut ever. Then I just disconnected the cables at the servo motor under the seat. I did not remove anything yet since I was not sure how the bike would react but maybe I can pull everything out and get some pictures this weekend since I now know I am keeping it disabled. Leaving the servo motor plugged into the system under the seat will ensure you do not throw a check engine light. Other option is buy a servo buddy or have the EXUP disabled in an ECU flash which is my plan. . Thanks...i tried |
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Post by deftone on Aug 20, 2016 20:59:02 GMT -7
From my first impression it seems like an easy way for Yamaha to get the bike quieter in the RPMs they test. I disabled my valve on day 2 and notice no negative characteristics...just better sound all the time. It is pretty easy to temporarily disable or permanently remove. Cool, I'll have to try this. My '98 R1 track bike ran like crap when I disabled the Exup. My impression was it was there to create back pressure to enhance low end torque. |
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danyboy24
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Post by danyboy24 on Aug 26, 2016 3:10:02 GMT -7
Yesss..i have better sound!!! Thanks
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chuckgraves
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Post by chuckgraves on Sept 16, 2016 17:15:58 GMT -7
Motorized actuating plates can fool the system into believing that it has more volume than it really does. This coupled with cross overs and cambers can smooth out the torque curve dramatically. The factories have done a tremendous job at this with rules being considered.
Think of it like this 14 PSI pushing at the back of the pipe and 14 PSI at the intake track. The waves are always changing. Anytime we can mechanically interrupt the 14 PSI at the tail pipe from affecting the exhaust speed at exit we are winning. This is a very simplified way of explaining it. I could write a book detailing the benefits of the mechanical valves.
Think about the exhaust stroke when its job is done exiting and the short period of overlap with the intake. During this period and depending on the RPM VS Throttle Position a condition can occur where the cylinder receives some of its filling from the exhaust port. This is bad!! It causes the exhaust speed to change and in some cases change direction. Change of direction can happen easily on a single cylinder machine much easier. Attacking the wave heading in the wrong direction is an art. Tappers, crossovers, collectors, motorized actuators, tubing diameters, silencer cores including hole sizes and pitch, shape of the silencer exit and much more.
Wiring the EXUP wide open with the stock system will in most cases cause a loss of power depending on the tuning of the EXUP from the factory. I cannot be sure on all bikes since I haven’t tested them all. I can tell you that there are gains to be had from EXUP on the FZ10 and R1. Flash the Graves Slip On map in a stock bike and you will see this. The maps are free to any user of FTECU software and downloadable from the FTECU file manager.
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kingcrimson
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Post by kingcrimson on Jul 2, 2017 2:56:04 GMT -7
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javahaxxor
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Post by javahaxxor on Sept 3, 2018 14:57:22 GMT -7
Motorized actuating plates can fool the system into believing that it has more volume than it really does. This coupled with cross overs and cambers can smooth out the torque curve dramatically. The factories have done a tremendous job at this with rules being considered.
Think of it like this 14 PSI pushing at the back of the pipe and 14 PSI at the intake track. The waves are always changing. Anytime we can mechanically interrupt the 14 PSI at the tail pipe from affecting the exhaust speed at exit we are winning. This is a very simplified way of explaining it. I could write a book detailing the benefits of the mechanical valves.
Think about the exhaust stroke when its job is done exiting and the short period of overlap with the intake. During this period and depending on the RPM VS Throttle Position a condition can occur where the cylinder receives some of its filling from the exhaust port. This is bad!! It causes the exhaust speed to change and in some cases change direction. Change of direction can happen easily on a single cylinder machine much easier. Attacking the wave heading in the wrong direction is an art. Tappers, crossovers, collectors, motorized actuators, tubing diameters, silencer cores including hole sizes and pitch, shape of the silencer exit and much more.
Wiring the EXUP wide open with the stock system will in most cases cause a loss of power depending on the tuning of the EXUP from the factory. I cannot be sure on all bikes since I haven’t tested them all. I can tell you that there are gains to be had from EXUP on the FZ10 and R1. Flash the Graves Slip On map in a stock bike and you will see this. The maps are free to any user of FTECU software and downloadable from the FTECU file manager.
There's always this know-it-all-barn-engineer-type that tells you how much power you make by doing the "Lars mod" (e.g. cut the airbox wide open on the FZ1), or "gut the cat", or like above, with wiring the exup open, like I also did. Being an engineer myself I've wondered if all these mods do more harm than good. The factory engineers put years of work in developing engines and exhausts, and the exhaust is the most costly after the engine (or so I've heard). But wiring it open is for free, when an Akra with tuning is a shitload of money, and I only have one flat spot that my ass dyno can feel, around 3-4k RPM when it hesitates on acceleration, so you have to wait for a second, kindof like a turbo lag. It's almost like the stupid Lars mod, that also made the bike choke before accelerating. I'm thinking I want to do another mod. Cut the EXUP out of the cat box and weld it onto a link pipe from LeoVince, I wonder if that's going to make things worse than now (probably). It would be interesting to hear more since you seem to be one of the few that understands this stuff. |
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Post by evitzee on Sept 3, 2018 15:15:17 GMT -7
^^^ The original poster you quote is long gone, he posted ONE time almost two years ago and then disappeard. Don't think you'll be hearing any more from him.
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Post by achrista on Sept 3, 2018 17:28:39 GMT -7
If that's the real chuck graves, he did develop an aftermarket exhaust with a butterfly valve in it. I have it on my bike. When doing WOT pulls, the bike runs rich from 5-6k revs.
Not sure if it would work, but you could try giving graves exhaust a call if you want to get a response.
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javahaxxor
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Post by javahaxxor on Sept 4, 2018 16:16:55 GMT -7
It would have been interesting in hearing more, but not so that I'd take time and make phonecalls and bother people.
I'm considering different exhaust mods to make my bike a little louder without loosing too much money or performance, but all i'm reading is just confusing me even more. Im thinking that gutting the cats in the OE box might be the one solution that interferes the least with the engineering that went into the design of the exhaust.
A video that goes into a bit of detail
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