YZ426 FMF Q4 Exhaust Diameter!

4 replies to this topic
  • ewd199

Posted August 15, 2009 - 12:58 PM


Hi, I need to get a Q4 exhaust but I need to know the diameter of the exhaust at the spot where it slips on to the header. My header is 1-7/8" of an inch and I need to know if it is the right size. I don't want to spend 300+ and have my header be to large or to small. If you know it will fit or you have the diameter please tell me! Thanks

  • TC33

Posted August 15, 2009 - 02:46 PM


I can measure mine if you want, but my Q4 came with 2-3 sleeves that I didn't need for the stock 09 header. I was a little concerned at first as the place where the pipes join doesn't use a clamp, but I slobbed it up with copper stuff (as the directions recommend) squeezed it together and waited till the next day to run it and it has been fine. It was a very tight fit over the stock header and the copper gasket stuff sealed it well, I have no backfiring.
Hope this helps!

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  • ewd199

Posted August 15, 2009 - 03:01 PM


Ya thanks for the info. my exhaust header is not stock that is why i am concerned, if you measure it for me i would really appreciate it. When you mentioned "sleeves", you mean like different types of fittings depending on your header size, right?

  • TC33

Posted August 15, 2009 - 04:04 PM


1.782 inches. The sleeves reduce the diameter for smaller header pipes. Of course this is a Q4 for a 09 450, I just noticed you specified a 426, sorry!

  • ewd199

Posted August 15, 2009 - 06:14 PM


do you think they are all pretty close to that size?

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