Frankenbuild Exhaust; the birth of the Yzwr.



I bought a complete powebomb style 2008 YZ exhaust for about 70 usd with a rather ugly muffler.

I also own a extra WR exhaust.


I do not like a loud exhaust, I do not care about the extra weight.




The idea is to remove the muffler from the rest of the YZ exhaust, calculate the flow for the WR muffler, and ad some holes to it.


The problem is that the YZ muffler and WR muffler isnt the same shape or size to just swap the front ends, also, pulling apart the front of the WR muffler is more a pain in the ass.


I have a one year old, a sick granny, a recently paraplegic wife, so this may take a while, but here are som pictures.



I had to stretch the muffler a bit with the tools i have right now, wich is a powerdrill, a AXE!, some wood, FIRE! and a metal saw.


Im skipping some pictures.


But basically:


  1.  Drill out rivets
  2. extract the back end, I wraped it in gasoline soaked cloth and lit it on fire, keeping the pipe in cold water, it all came out by some manual labour.
  3. cut some wood to the correct shape with a slight conical shape
  4. Use the axe and stricke the mufflermounting, it seems hard enough
  5. cut some groves in the back part of the YZ exhaust, bend it togheter again


I really dont think after doing the work that the muffler needs any expanding, its easier to just cut more in the YZ tailpipe and weld it.



I will continue the list when i have some progress, and do a better wrightup at the end.




And for the ones whos asking why the hell are you doing this?


I need the alone time in the barn, and i do not have another projekt to mess around with.


Need to keep the hands busy you know.


Also if I´m hard to understand, ask, english is not my first language.









the YZ pipe with the back end of the WR muffler mock up for fitting.


More about the muffler later on.


Anyone knows what steel the exhaust is made of?





Cool, looks like awesome Riding terrain in the background!!! Where is that ?

Cool, looks like awesome Riding terrain in the background!!! Where is that ?

Nah, northern Sweden, the ice age made the landscape full of boulders and it's really dense Forest, yo can only ride timbertrails or sled trails.

Update regarding the pipe, the header is the bigger 2008 OEM yz450 powerbomb version, I hope this will work well with a muffler that has a little bit higher flow resistance then normal

A little bit on the way, now on to the muffler for flow and sound volume.

Then there will be a shitload of polishing and sandpappering



So i made some progress but no Pictures today.

I tested it with a completely empty wr can with just a spark arrestor today and the thing really BRAAAAP;s compared to the euro gytr pipe I had earlier.

But the yz pipe puts of a lot of heat, and I mean a lot.

Do I need to re-jet?

Can I check this in some easy way?

I already set the carburetor up as suggested in the FAQ, and it's running great, but hot

Edited by Agazza

Did you guys know that the original European pipe has a catalyst in the muffler?


It's actually a decent size, would love it on the yz pipe, think it reduces a lot of noice



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