header pipe diameter?

12 replies to this topic
  • xtratoy

Posted June 14, 2007 - 07:39 PM


What is the outside diameter measurement of the Yosh RS2 full system header pipe and the 400E pipe? :thumbsup: I have a 400S and was wondering how much larger the other two header pipes are. Mine measures 1 1/2" O.D. The only other 400 I have seen to check was a Quad with the 400 c.c. motor in it. It had the keihin carb and its header pipe was 1 1/2" O.D. I don't know if the quads share the same exhaust system as the 400E.

  • Skidder

Posted June 15, 2007 - 01:37 AM


I don't know the exact measurement but look at it this way. I'm pretty sure all aftermarket exhaust companys must use the larger diameter (E) size tubing. What performance good would it do to make it smaller and also have fitment issues? I run a stainless E model White Brothers head pipe and it fit right into my FMF Q mid pipe/ can.

  • xtratoy

Posted June 15, 2007 - 09:07 AM


thanks for the answer, but not the info I asked for. Can someone throw a caliper on their Yosh header pipe or 400E pipe?

  • xtratoy

Posted June 15, 2007 - 04:24 PM


BTT someone must know the answer.

  • Bermudacat

Posted June 15, 2007 - 04:30 PM


The Yoshi ti port is just a RCH under 39mm

  • supermotogreg

Posted June 15, 2007 - 04:53 PM


Hi toy, :busted:

The E headpipe outside diameter is 50mm,
and the S/SM headpipe outside diameter is 47mm. :thumbsup:

Had to wait a little while for mine to cool off... :thumbsup:

Take Care,


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  • gizmoe

Posted June 16, 2007 - 04:08 PM


It all depends where you measure it...
My E header was about 41mm & the staintune was about 45mm...

  • supermotogreg

Posted June 17, 2007 - 08:13 AM


You're right... I measured the tubing diameter reading the wrong end of the vernier! :thumbsup:

Thanks for the correction...:thumbsup:


  • xtratoy

Posted June 17, 2007 - 08:41 AM


Posted Image
This is where I have been measuring for comparision.
I'm just trying to find out if the yosh pipes are significantly larger before I install my jet kit, MCCT, and other parts I got yesterday from the TT store. I'll wait to rejet if I decide to Yosh it. 2007 DRZ400S 175 miles on the odometer

  • Eddie Sisneros

Posted June 17, 2007 - 09:31 AM


the head pipe diameter is only a small part of the equation.

  • xtratoy

Posted June 17, 2007 - 09:56 AM


So forget the full system and just do a slip-on ?????? Use the stock small header pipe and and rejet for it?? I plan on leaving the motor S stock except for 3x3, rejet and exhaust. are you saying the yosh upgrade isn't needed? Bike will be a 50/50 street/trail ride.

  • Eddie Sisneros

Posted June 17, 2007 - 10:48 AM


uh,no thats not what i said.

i said the head pipe diameter is only one part of it.there is also length,taper,how much mega phone is built into the muffler.

slip ons make alot of noise and little gain.

  • xtratoy

Posted June 17, 2007 - 11:00 AM


Eddie. thanks for the clarification. :thumbsup:

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