Is my exhaust legal?

9 replies to this topic
  • 1gdsm4life

Posted October 09, 2007 - 06:47 PM


i have a 05' yz450f and i was wondering if my stock exhaust is forest legal?
any info would be very helpful,

Thank You, and God Bless

  • 06crf_er

Posted October 09, 2007 - 06:52 PM


Most likely not. All "motocross" bikes are designed with closed course only pipes. An easy way to tell if a pipe is legal for use in the state or federally owned land is to see if it is stamped with the U.S Forest service stamp stating that it is approved for off highway use. offers U.S. Forest Service approval stamped end caps that replace your stock end cap. They might have something for yuour application. If not, many pipe manufacturers have many options to get you legal for the woods:thumbsup:

  • KAS

Posted October 09, 2007 - 06:57 PM


No, a stock exhaust is not legal. There is no spark arrestor. If you want to get legal on the cheap, like was said above you can get a Pro Moto Billet spark arrestor end cap for a fraction of the cost of an aftermarket pipe.

Thats what I've done with my '07 and it works fine.

  • B-LAGO

Posted October 10, 2007 - 02:21 PM


It might also be worth looking into a cheap slip-on exhaust system. I might be wrong, but the promotobillet end caps can really hurt performance on some of these bikes. A white brothers XCR might be a good solution, for just a little bit more money.

  • KAS

Posted October 10, 2007 - 03:06 PM


I might be wrong, but the promotobillet end caps can really hurt performance on some of these bikes.

How do you figure? The only thing you're doing is basically adding a screen so its spark arrestor legal.

My bike didn't lose anything.

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  • Butta

Posted October 10, 2007 - 08:37 PM


If all else fails, I have an FMF Ti Q on my '05 450 that I'd sell to you. PM me if interested.

  • Birdy426

Posted October 10, 2007 - 09:35 PM


No performance hit with the PMB end cap. Note that the S/A alone doesn't get you legal. You need to be at 98db as well. PMB Quiet Insert will get you there, and if you can feel the performance hit your rectal dyno is a heck of a lot more sensitive than mine.

  • KAS

Posted October 11, 2007 - 06:10 AM


Oregon statewide dB limit is 99dB

Except in the dunes, its 93.

I know my '07 stock exhaust will pass 99, I'm not sure about the '05.

  • tnl

Posted October 11, 2007 - 06:55 AM


The PMB set up with the silent insert is the cheapest set up that your gonna find on a new system! I don't feel the loss of any power with the insert in on mine. I think it's worth it.

  • BBrown626

Posted October 11, 2007 - 07:58 AM


Try a Power Core IV Ti with spark arrestor. They claim 99db without the core. With the core I think 96. Big difference in airflow requires rejetting or just being content with poor performance with the insert in. I have this configuration and it worked well with the insert for trail riding during vacation in the Oregon mountains. I normally ride Mx in socal and the muffler is great without the screen and insert. I do notice the difference with the screen in too, but not a lot.


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