YZ muffler on a 09 WR

Will a muffler off of an aluminum frame yz450 fit on my 09 wr450? I was told it would but read other wise in another post. Would it need to be modified?


yes it will work, make sure you get the yz header to go with it. I'd recommend the 06 exhaust from the yz's, or if you can't find 06 on ebay, find an 07.



Just to clarify what erickdj said:

It will fit, no problem, but you will need to modify the seal between the OEM WR450F header and the new muffler.

This is easy to do, (have a look at it when you pull the muffler off the bike) you might need to add a little silicon muffler sealant to seal the joint up completely.

A better/easier option would be to get hold of the YZ header (as erickdj suggests). That way you will have the added advantage of the bigger diameter pipe. The WR450F header is a few mm smaller in diameter than the YZ450F unit.

I went the other way with my '08 WR450F: I used the YZ450F header and opened the OEM WR450F muffler right up to match it.


I've since fitted a Powerbomb style header off an '09 YZ450F ......to replace the '08 YZ450F (non-Powerbomb) one I had on it previously.

Interestingly: The '08 (non-Powerbomb) item is a larger diameter than the '09 (Powerbomb) one and it tapers by about 3-4mm in diameter too.

I can't feel any difference between the two YZ450F headers when riding the bike.


Yeah, I should have been more specific about why I recommended getting the yz header to go along with it. Greg is right, the wr header will work, but you'll need a wr muffler gasket for it to seal properly. The stock yz exhausts can be found pretty darn cheap on ebay so it makes sense to get both the muffler and header together. Good price/performance ratio.

I want to keep my wr header to help keep my bottom end power is why I asked. The larger the mid pipe the geater the top end. I won't to keep as much bottom end as possible. And still keep the bike fairly quiet.


I got an 08 YZ muffler and head pipe off ebay and they fit my 08 wr perfect. Heluva lot cheaper than aftermarket exhaust.

My buddy greg claims the larger head pipe helped torque quite a bit. I would say my new setup with the larger head pipe has much better bottom end power than the stock setup with the uncorked tip.

I also bought the promoto spark arrestor and both the quiet and ultra quiet tips.

The guys at hollister have sound tested both tips for me. They said the quiet tip was 98 db and the ultra quiet was 97.5 db..... they gave me the sticker both times anyways. I might need to repack the muffler.

I want a quieter muffler, but I really like how the YZ one is short and light. The whole system swap saved 3lbs.

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