WR exhaust

Does anyone know if a stock YZ 426 exhaust will fit the WR 426? If so, would there be any problems with the jetting? Or would the jetting be similar to, say, an FMF silencer?



Yes it does fit, but will have to alter jetting as you will probally be running lean.

You will have to pick up maybe four parts from the dealer depending of what you got with the YZ can (the rubber collar, damper, washer, and bolt).

16 bolt $1.08 95817-08030-00

17 washer $0.75 90201-081R9-00

19 collar $6.20 90387-0814J-00

18 damper $2.61 5BE-14714-00-00

There really isn't much flow difference between the uncorked WR and stock YZ cans. I was already running the YZ jetting before I swapped and didn't notice a difference after. The muffler swap is mostly a weight issue, that is the noticable difference.

I'm not too worried about the weight issue, I'm 275, so I doubt I will notice the pound or two difference.

I bought the pipe because I had already purchased an FMF power core 4, then I found out it doesn't just "slip on" it's another $150 for the header, so I picked up the YZ can for a song, should I go ahead and pay for the header, or is it a waste of money (the YZ will do??)

It was already jetted for the FMF, which I didn't install, but the WR is uncorked, and there are gobs more power, but it pops a little when I let off the throttle.

Just looking for opinions, there seems to be some wise ones around here. Thanks :)

I swapped my wr pipe for a yz pipe and the bike ran much stronger. The nearly four pounds difference in weight IS noticeable because it is all carried high on the bike. I did not need to rejet (at 2000 ft) but am using a PMB spark arrestor with a silent insert so the restriction was somewhat similar to the vortip I used with the WR pipe.

Didn't your PC4 come with a reduction spacer? The PC4 I got a few weeks came with that and it slipped right on my stock header pipe. It should be the same for the 450. Perhaps the spacer was missing from your kit? :)

Talk about timing ! :D

I intend to install a YZ pipe model 2001 on my canadian wr 426 2002, and I was wondering about the same things.

Will it fit right on ?

What are the parts needed ?

What changes will have to be made to the jetting ?

And finally, the canadian WR pipe is welded a the end, we can't just uncorke it. The opening is about the size of a quarter.

What difference will the YZ pipe bring :D?

Will I lose low rpm torque :D?

What else :)?


Uncorking it brings more power everywhere, including low-end torque. My change-over was an easy bolt-on - and as I mentioned before no jetting changes were necessary - I still run stock jetting. The toughest part is the slip-fit gasket - you need to be careful not to damage it too badly during the exchange. My wr is an 02, the yz pipe was an 01.

It seems that you have exactly the set up I'm looking for. :)

When you say that you installed a PMB spark arrestor with a silent insert . Where did you get this ?


I purchased my PC 4 at the FMF factory in Compton, it was at their 'scratch, dent, and ding' sale. It was just the slip on with no accessories, and the salesman told me that it should slip right on (typical salesman)

I went to get it installed and jetted at Chaparral, and they told me about the different size, so I picked up the YZ can.

The YZ silencer will be quieter than the PC4 any way. Good move.

Pro Moto Billet - I don't have their phone number handy but they advertise on TT :)

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now