Just Shortened my 04 450f Silencer, Looks Sounds Good

28 replies to this topic
  • crf450f

Posted June 09, 2004 - 06:05 AM


Just Shortened my 04 450f Silencer, Looks, Sounds, and feels like it has more low end. Cut off 5 inches from end, and rivet the end cap back on. Anyone els did this mod? :thumbsup:

  • Sean_McCutcheon

Posted June 09, 2004 - 06:55 AM


I have never thought of that. I don't like how long the silencer is in the first place. I have been trying to find an aftermarket exaust that is shorter than the stock one. Now I can save $300 and just cut the stock off. Does anybody see a problem with doing this?

  • crf450f

Posted June 09, 2004 - 07:29 AM


remember , when you cut it off, make sure you cut the outside aluminum, Leave the inside baffle tube a little longer so it goes into the pipe end.

  • crf450f

Posted June 09, 2004 - 07:31 AM


I hate how long it was too, stands out like a sore thumb, he he

  • crf450f

Posted June 09, 2004 - 07:35 AM


Took my 04 450f with pipe mod, and smoked my buddy riding a 2 stroke, Pipe working great! So much low end!

  • yz_for_me

Posted June 09, 2004 - 08:20 AM


Anyone els did this mod? :thumbsup:

Yea, Petersonracing did it. Here's the thread.


Posted June 09, 2004 - 08:24 AM


Did u notice much difference in the top end? I did this to my 03 yz250f but only 3 inches off a nd it felt like i had more torque but also seemed as if it started pulling harder sooner in the midrange right before it got to the top end of power if that makes sense?

  • Sean_McCutcheon

Posted June 09, 2004 - 09:15 AM


So basically what I need to do is take the pipe off and take the insert out by drilling all the rivots out. I just ordered the PMB insert anyway, so I was going to have to do this step soon. Then cut 3-5 inches off the pipe and then put the new PMB insert on. Did you cut it with a hack saw?

  • YZFmunky

Posted June 09, 2004 - 04:03 PM


so whos gonna dyno it so we can see exactly what the change is?

  • Sean_McCutcheon

Posted June 10, 2004 - 01:29 AM


Also, what kind of effect does it do to your back pressure, because if you don't have the correct back pressure it can be hard on your valves.

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  • crf450f

Posted June 10, 2004 - 10:28 AM


The backpressure shuld be close to stock, because the primary restriction is located at the end cap.

  • John407

Posted June 10, 2004 - 04:45 PM


I thought the length of the entire exhaust system was important. That is why to move the silencer ahead they had to make the low boy pipe. I'd love it if this mod works but I don't see how it can.

  • Sean_McCutcheon

Posted June 11, 2004 - 01:39 AM


The length of the exaust is important or they wouldn't make them that long in the first place.

  • Sean_McCutcheon

Posted June 11, 2004 - 01:42 AM


Did you use a band saw to cut the exaust?

  • Vet28

Posted June 11, 2004 - 02:25 AM


Has anyone notice the ring welded into the end of the stock can in 2004? My 2003 stock muffler had a larger diameter than the 2004. You can see a little ring welded into the end cap.


  • felony

Posted June 12, 2004 - 06:13 PM


the longer silencer helps to keep the noise down somewhat,thats why most smaller aftermarket ones are louder than stock.this is a popular mod,it does tend to add a lil'mo lowend over stock.i wouldnt cut more than 3 or 4in max off myself though,some back pressure is needed to keep exhaust temp under control. :thumbsup:

  • crf450f

Posted June 22, 2004 - 04:48 AM


still running great! taking it back to the track tomarow, broom broom. :thumbsup:

  • 450GN

Posted June 22, 2004 - 12:12 PM


glad to hear
now i am interested... free power is the best
now what did you cut the pipe with?

thanks in advance :thumbsup:

  • rbm33

Posted June 23, 2004 - 01:27 AM


why not just use a stock 250f muffler??

  • rpyfz450

Posted June 23, 2004 - 08:22 AM


i wouldnt cut more than 3 or 4in max off myself though,some back pressure is needed to keep exhaust temp under control.

Wouldn't reduced backpressure also reduce exhaust temperatures?

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