Exhaust Pr0n: Yoshimura RS-4D

Dailies, Galleries -


The science behind this new Yoshimura RS-4D exhaust sounds simple — two holes are larger than one and that increased outlet area flows burnt hydrocarbons easier. But, in addition to the boost in top-end horsepower typically associated with freer-flowing exhausts, Yoshimura is also claiming increased low-rev torque. Regardless, it’s the unique two-outlet looks that make the RS-4D stand out.

Developed for use on Ryan Dungey’s Supercross RM-Z450, the full-titanium system is also available for the Suzuki RM-Z250, Honda CRF450R and CRF250R. Both titanium and carbon canisters are available, but both come with carbon endcaps.


  • Glenngineer

    Nice looking pipe. I dig the hanger.

  • fasterfaster

    That science doesn’t really make sense as described. One large hole is bigger than two small ones, i.e. a 2″ hole is significantly larger than two 1″ holes. Maybe it’s increased outlet size and surface area for a given exhaust WIDTH. That would make sense, but so would an oval outlet.
    Whatever the case, the truth is in the dyno..

    • http://hellforleathermagazine.com Wes Siler

      Indeed, but if I include an enormous disclaimer with each and every article you wouldn’t get the chance to correct me, would you?

      • nick2ny

        A-ha! All the errors on Jalopnik since you left must be there to promote reader involvement!

        • http://hellforleathermagazine.com Wes Siler

          Just imagine how bad the driving’s gotten.

          • Tony

            If the gawker redesign is any sign, its probably become pretty awful.

  • noone1569

    Wonder if I could adapt this to fit my XB12R mounted horizontally underslung. . .

  • http://rohorn.blogspot.com rohorn

    I see the marketing guru behind Honda’s “Placebo Engineering & Propaganda” division works for Yoshimura now…

    • http://hellforleathermagazine.com Wes Siler

      Ha, you assume there’s only one?

      • Glenngineer


  • gregorbean

    In the words of Paris Hilton, “That’s hottt.” I don’t know about carbon endcaps for bikes that are inevitably going to get dumped a lot, but damn they look good…if they made one for the XR650R and I didn’t already have an aftermarket pipe on my bike, I’d be considering this for sure.

    • gregorbean

      I can’t believe I just quoted Paris Hilton. Fail.

  • seanslides

    I don’t know man, that’s twice as many muffler bearings to replace.

  • http://www.damiengaudet.blogspot.com damien

    holy mini rocket ship, batman! looks pretty cool.

  • Peter

    Ruckus owners probably just creamed their jeans.