Using a YZ muffler questions

[MountainMax]

Hey guys, I just installed an 05 YZ450 pipe on my 06 WR450 and it sounds awesome, what a size of a tailpipe, makes the promoto billet insert look small in comparison. Anyhow I was wondering if just this mod will need a jetting change? I have all free type mods done already and jetted as per the sticky above.. I noticed the acutal pipe that goes into the muffler is also way larger then the WR one and like i said the tailpipe is huge, I had to offset my Liscence plate a bit to clear it.

[XRYoda]

The jetting was the same for me as with the Promoto Billit...

[old man dan]

Same here, didn't change jetting other than slight tweak of fuel screw. I pulled the plug and it looks perfect.

[odonnks]

Hey guys, I just installed an 05 YZ450 pipe on my 06 WR450 and it sounds awesome, what a size of a tailpipe, makes the promoto billet insert look small in comparison. Anyhow I was wondering if just this mod will need a jetting change? I have all free type mods done already and jetted as per the sticky above.. I noticed the acutal pipe that goes into the muffler is also way larger then the WR one and like i said the tailpipe is huge, I had to offset my Liscence plate a bit to clear it.

Did you use the YZ headpipe ? or stay with the WR's?

[Looks450]

I didn't touch the jetting, and to be honest i don't think i could tell if i need to adjust the fuel screw. Cheers

Looks

[bg10459]

Did you use the YZ headpipe ? or stay with the WR's?

The YZ and WR headpipes are the same. The YFZ headpipe will work, too. The only difference is it's stainless rather than titanium.

As far as re-jetting, I had to after going from the open WR exhaust to the YZ. The main was the biggest issue.

[MichielD]

Max, I did the same conversion on my 400, upped the main slightly (165- 168) and tweaked the screw. Seems great now!! The thing is loud though, turns heads on the road!!!

[MountainMax]

thanks guys, I am using the stock WR headpipe as they look identical to the yz one, but the pipe going into the yz muffler is way larger then the wr one, and the outlet is huge, almost as big as the headpipe, I like it......

[odonnks]

I just received my Ebay purchased YZ pipe. Won't be able to try it till Thurs.

Paid a whole 26.00 and its in perfect shape.

I'm sure it'll be pretty loud. Probably nore than I'll want.

Is there any easy way to quiet it up some?

Thanks

[MountainMax]

Wow Great Price, I paid 9.99 for mine but 50 for shipping....... and im happy, the only way I know to make it quiet is either to just lay off the gas and it's ok, i drive mine on the road with no complaints yet but i have to take it easy, less then 1/4 throttle.... once i Open her up, man what a roar..... I noticed I may have lost a little bottom end with this muffler though, and gained on top, anyone else notice this??

[odonnks]

To take the 'Bark' off the YZ pipe I was thinking about removing the end cap and installing the one from the WR silencer with only the arrestor.

I noticed that with the WR silencer and second baffle removed, and no tail pipe there was a difference in sharpness with only the arrestor installed.

It looks like the YZ's oval pipe is the same dimensions.

Has anyone tried this?

[MountainMax]

I was looking at this and wondered the same thing, however the YZ tip is rivoted in and the wr is scrweed in, not sure if the holes are in the same place.... the spark arrestor will definately m ake it a bit quieter.

[boer]

Wow Great Price, I paid 9.99 for mine but 50 for shipping....... and im happy, the only way I know to make it quiet is either to just lay off the gas and it's ok, i drive mine on the road with no complaints yet but i have to take it easy, less then 1/4 throttle.... once i Open her up, man what a roar..... I noticed I may have lost a little bottom end with this muffler though, and gained on top, anyone else notice this??

Has anyone else experienced the loss Max had on the bottom end? This concerns me as this is were I want to gain some extra response ?

[MountainMax]

Actually I think i have that solved now with jetting, she now feels stronger right through the entire power band, sorry for not posting this info earlier, She really likes to be rich, im running a 50 pilot jet, 40 leak jet, 170 main jet, 72 starter jet and the needle clip dropped olne notch. all is well now except i need 3 turns out on the adjuster scrrew to keep from getting a scattered decel pop.........duct tape to keep her in this time.

[boer]

Hey Max,

So the YZ pipe breathes better than the aftermarket pipes or why else would you need such rich mixture? ? What was your jetting with the PMB insert before the YZ exhaust?

Did everybody else need to re-jet that rich too after changing to the YZ pipe?

[MountainMax]

I was using indys spec before the yz exhaust and exhaust cam, then i had to bump it all up one notch...... Breaths much better, the yz muffler has a larger inlet pipe, same size as header, and a way larger tailpipe then the PMB and it's straight thru.

[bg10459]

Wow Max, That jetting seems real rich. The only person I ever heard using larger than a 48 PJ had his slide in up side down. with a 50 at 3 turns out you're unbelievably real rich. You might want to check it if you've ever had the slide out, and even if you haven't, because I've heard of it being in wrong from the factory.

FWIW, I'm using the YZ pipe and I usually go with a 48 PJ, but switch to a 45 when it gets over 90-95. 168 MJ when it's that hot, normally I use a 165, and switch to a 160 for the winter.

[MountainMax]

I never had my slide out, and took pics of it and posted here, the boys said it's in right, and she don't run rich or put out black smoke, strange but true, I am sea level and it's pretty cold where i ride, average temp is about 60 degrees i guess......