posted March 25, 2004 02:02 PM
Let's revisit the exhaust, the power valve... So... someone correct me if I am wrong.. the outcome of the previous thread that discussed this was that the exhaust vavle did little more than modulate the exhaust sound for noise regulations? Am I correct in remembering this? kbryant?
Someone dig up the thread as I am too lazy to do so myself ____________ What business is it of yours where I'm from, Friendo?
posted March 25, 2004 02:48 PM
you miss my point...we've already had this discussion... there wasd a different outcome than what you say..
____________ What business is it of yours where I'm from, Friendo?
posted March 25, 2004 04:03 PM
Power Valve Fish Antlers,
Joe is correct, whilst the valve does regulate noise/emmisions it's main function is to reverb exhaust gas back down the exhaust which makes the engine burn more efficiently and boosts low/mid range power.
The valve also helps the bike pass the EU & EPA noise tests which are usually set at 4500-5500 rpm, hence the normal power dip at these revs.
posted March 25, 2004 04:35 PM
Edited By: k bryant on 25 Mar 2004 16:39
Here is what I stated/found from some previous opinions of mine;
quote:One little known fact that most people miss out on when it comes to the valves in the exhaust; No matter what the design concept, whether it's Yamaha, Honda, Kawasaki, Buell, or whatever version, a primary reason is sound. The valve attenuates sounds levels substantially during EC/EPA testing procedures. In a big way, it allows for much more non-restrictive mufflers, because the valve actuation limits the flow. Henceforth, the sound level. We first found this back in the 80's when testing Japan spec FZR400's with the first version of the "EXUP" valves.
quote:redelk - No. Wasn't implying that. They definetly provide better low-end & mid-range power. It pretty much makes common sense. Big diameter pipes and/or free flowing mufflers can ruin power at low/mid rpm's. With an in-line valve closing off some of the flow at those rpm's, you gain the necessary back-pressure to make them perform well. At higher rpm, when the valves are open, you gain the full advantage of bigger tubes & non-restrictive mufflers.
As to the rest of your dribble (though excellent), you are pretty much spot on. Nice job!
posted March 25, 2004 05:02 PM
guys.. dont get me wrong.,.. I appreciate the responses... I am pretty clear on the function of the valve... I am just trying to draw 2 certain parties on this site into a discussion as they share "slightly" different view on the subject...
____________ What business is it of yours where I'm from, Friendo?
posted March 25, 2004 07:59 PM
Bottom line is it restricts exhaust flow.... noise be damned...
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posted March 25, 2004 08:08 PM
bottom line is get rid if it. First mods that were done on my gixxer 1000's. first mod i will do on my 10r, with the aftermarket exhaust of course.
posted March 25, 2004 09:01 PM
if it actually helps in low to mid range performance without sacrificing
top end, why the rush to get rid of it? it seems like sound technology
thats the best of both worlds, or am i missing something. could someone
please explain?
____________ ''The angle of my dangle is inversely proportional to the heat of my meat''Will Ferrell
quote:if it actually helps in low to mid range performance without sacrificing
top end, why the rush to get rid of it? it seems like sound technology
thats the best of both worlds, or am i missing something. could someone
please explain?
well, the factory pipes are a blend of performance to match emissions... Aftermarket pipes open up the top end plenty more and with a good map & dyno time you regain the low and mid.
posted March 25, 2004 09:17 PM
roger, roger. thanks.
____________ ''The angle of my dangle is inversely proportional to the heat of my meat''Will Ferrell
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posted March 25, 2004 02:02 PM
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