exhaust pipe diameter, length and volume.

there is a long thread over at the YZ forum about "the loudest pipe", mostly about land usage. i have been doing some exhaust changes, trying to find a quiet off road setup.

my setup - stock headpipe and a 17" fmf ti-4 with a quiet core insert. i have tried the 14" ti-4 with the quiet core but the pipe feels restricted, with the 17", the quiet core doesnt restrict the flow so much. :thumbsup: the endcap is the same on both pipes but the 17" runs so much better.

the only reason i can see is that the 17" has more volume, and that lets the exhaust expand in the pipe before coming out the endcap, giving a less restricted feel. having said that, the 14"/quiet core setup is quieter and more restricted than the 17" setup.

with the pipe companies trying to make quiet pipes, why dont they experiment with more pipe volume? maybe this is the way to get rid of some noise while making the bike feel less restricted?

Kind of like the huge exhaust yamaha puts on the warrior cruisers. Hop on over to their website and check it out, the thing has got to be at least 10, if not 12 inches in diameter

Some day we will all have 55 gallon drum silencers on the back of our bikes! :thumbsup::lol::awww:

I am sure the pipe diameter has a play with bottom end torque and driveablity. Just take you header off and ride around the block you will see what I mean. :devil:

im not talking about no giant muffler...

i was wondering if anyone had some technical info about exhaust dimensions. i have 2 headpipes - stock yzf and a WB tapered header. the stock headpipe has a consistant diameter and appears to be longer, the WB header is shorter but tapered to a larger diameter.

the stock header gives great throttle response with solid bottom and lots of top. the WB header bogs off idle and, while it seems a little torqier, it doesnt add power and doesnt seem worth the trade off. does the WB header have too much volume for my engine?

another thing that makes me scratch my head is that the stock headpipe prefers a 1 3/4" reducer at the endcap, while the WB headpipe hates the 1 3/4" reducer and needs a 2" outlet. not to mention the fuel screw needs to be turned out a 1/2 turn to accomodate the WB header.

why is this?

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