Kawasaki Sportsbike Riders Club - Australia - Online Forum

Gosling1 wrote:My flapper valves sit on the bench, right next to the flux capacitors and the flange oscillators..........

I hope you did leave the "Go faster Stripes " on though

Strika wrote:

Gosling1 wrote:My flapper valves sit on the bench, right next to the flux capacitors and the flange oscillators..........

OK, I.K. will probably have my guts for garters for this!!!! But i disagree with his statement that the exhaust valve removal will rob the bike of bottom end or midrange. I know from dyno graphs (Before and afters) on both a mates ZX6R (05), and Dangerous Dave's R1 that removal of the valve did nothing to rob any bottom or mid, in actual fact on the R1 it picked up on both. Then once a set of fufflers was fitted, it increased again along with an increase in peak power.

As for mufflers for the 636, and Akrapovich is one of the best I have seen. When Gavin cosway first built Shris Seatons bike in 05, he couldn't get hold of a full Akra, and used a slip on for the first race. When the full system was put on it, it made 2 more HP, right at the top with no noticeable diference anywhere else. I would be inclined to just stick an Akrapovich muffler on it. And FWIW it also made a little more power througout the rev range than a couple of other systems that they tried.

That wasn't I.K., that was me showing me lack of exacting exhaust knowledge. I was just going on a set of dyno graphs I saw between a ZX10 with stock system, Akra cans and a full Akra system.

Just save your money, chuck on a slip on pipe, if it runs like sh*t, then fork out for a PC, filter and dyno then, if it doesnt and you dont need those last 4 horsepower, then just enjoy your new sweet sounding bike

Strika wrote:

Gosling1 wrote:My flapper valves sit on the bench, right next to the flux capacitors and the flange oscillators..........

OK, I.K. will probably have my guts for garters for this!!!! But i disagree with his statement that the exhaust valve removal will rob the bike of bottom end or midrange.

Um, dude, I've been saying pretty much the opposite... ditch the stock exhaust and the torque curve as a whole shifts up, but the lumps in it become more proportionally pronounced...

Mick's probably got it right with his statement about the simple, link-pipe or muffler-mounted flapper valves like on the ZX6 and 10, the current R6 and the various flavours of GSX-R. By the time the exhaust gas reaches them, all the pressure-wave action's pretty much done and over with. The collector-mounted systems, like on the R1 and the 929 and 954 FireBlade stand a chance of doing something.

FrogZ wrote:As long as we are getting technical can someone explain how the flattened part of my Micron serpent headers work.

It's to decrease the difference in gas velocity and pressure between the section of the pipe at the inside of the bend and the outside of the bend.

Let me try an analogy here...

Picture a two-lane roundabout with two cars entering it together from the same direction at the same speed, one in the inside lane, the other in the outside, both of them turning right with the aim being to have them also exit the roundabout neck and neck. The car in the inside lane has a shorter distance to travel around the roundabout than the car in the outside lane, so if they enter the roundabout together, for them to leave it together, the car in the outside lane has to travel faster than the car in the inside lane.

This is what happens inside the bent sections of exhaust pipe. If you take a piece of pipe and you start feeding gas in at one end, if the flow is in a steady state (this doesn't entirely hold true for a cycling engine, which feeds gas in in pulses, but it applies insofar as to explain the cobra-like variation in cross-section in high-end aftermarket header pipes... interestingly, top-shelf systems used by race teams still use circular cross-section tubing throughout), what goes into the pipe at one end has to be matched exactly by what comes out of the pipe at the other end... otherwise, there's either more or less gas leaving than there is going in, and the density of gas inside the piece of pipe is changing as a result; this is not a steady state.

Ok so far?

Now, for a straight piece of pipe, this is a no brainer. Gas entering at any point in the pipe cross-section has the same distance to travel as the gas entering at any other point, so any single cross-sectional "slice" of gas enters and emerges from the pipe together, at the same speed.

But, if we bend the pipe, the gas entering at a point towards the inside of the bend now has a shorter distance to travel than the gas entering at a point towards the outside of the bend, and, as a result, has to flow faster to compensate. What actually happens is that, because flow impedance of a curved path for a flow is proportional to the radius of curvature, the gas towards the inside of the bend slows down and the gas towards the outside speeds up.

This is bad for an exhaust because it creates a density, and hence pressure differential (gradient, to use the strict terminology) across the cross-section of the gas flow; effectively, the gas gets "stretched" at the outside of the bend and "squished" at the inside. This causes a twofold detrimental effect; first, the gas tries to expand down the direction of the pressure gradient, ie. perpendicular across the pipe cross-section, and the "chafing" of the faster-flowing and the slower-flowing gas on each other causes them to "trip" each other up. Both of these are sources of turbulence, and the flow impedance of a turbulent flow is much greater than the flow impedance of an orderly, laminar flow. This means that an engine has to spend more of the energy it produces getting rid of its own exhaust gas if the flow of that gas in the engine's exhaust pipe is turbulent than if the flow is laminar. In addition, a turbulent flow has the effect of eroding any pressure waves propagating through it, which means that an engine with turbulent flow in the exhaust won't scavenge its cylinders as effectively as an engine with laminar flow.

The idea behind the hydroformed serpent headers is to reduce the path length difference around the bend between gases at the inside of the bend and the gases at the outside of the bend, so the above-outlined differences in gas speed, and thus the turbulence they cause, are minimised, and they achieve this throughout the rev range.

I-K you are a bloody guru
Not only for knowing it but for putting it in such a way that a dork like me can understand.
Thank you

Hardly. All I did was get a physics degree instead of a computing one...

ok, so dose anyone know any thing about micron exhausts>??? i was told that they worked well on the 636 , and are a ok price...been quoted $3200 for full system plus power commander III , filter . all dyno tune... say 10-15hp from the micron ...


http://news.micronexhaust.com/newproducts.php/52

Micron make great exhausts.

But shop around, there are many other exhaust manufacturers out there. And all of them sound subtly different

myy636 wrote:ok, so dose anyone know any thing about micron exhausts>

They're up there. Quality of manufacture on the systems is good (the mufflers come apart with Allen bolts for repacking) and they're well-represented among race teams in national-level racing overseas, especially in the UK; that's the true test of how an exhaust performs.

i was told that they worked well on the 636 , and are a ok price...been quoted $3200 for full system plus power commander III , filter . all dyno tune...

At that price, wait for a used one to pop up.

I know the Microns work well on Dangerous Daves R1, but couldn't tell you about the 05 636 pipe. Ask the Superstock guys what they ran? They may have an Idea!

Strika wrote:I know the Microns work well on Dangerous Daves R1, but couldn't tell you about the 05 636 pipe. Ask the Superstock guys what they ran? They may have an Idea!

yep, only slipons allowed in asc superstock, no PCIII's allowed either

just also would like to know if the bike needs a power commander if a slip on is added. my mate as a 06 gsxr1000 and he could not just run it when bolt on slip on. could not run it properly and i cant remember why but apparently this is common for the gsxr so he had to take it to the dealer to do something to make it run ok.

that sounds really odd - its *just* a muffler, and changing it really will not effect the bike so much that it won't run at all, or run so poorly that it needs a dealer to service it ....

If you only fit a slip-on pipe to your 6, you should be fine without a PCIII. Its when you get a full system, better filters etc, that a PCIII really can add some value to the whole thing.

And 3200bucks ?? No way - get a system direct off e-bay it will cost less than 1/2 that amount.....

hmmm $3200.... spend the money on race glass, suspension set up, track days and ride schools.... you'll come out a better rider... and have more fun, than cruising the cafe strip sounding good!......

Serioulsy, you have a bike with more power than you really need.... and at the end of the day you can give it the caning it so deserves on the track!