Modified stock pipe saves big $$$

[MKP]

WR_Dave:

Need an answer:

Can I ride without the tail pipe ??? ?

Just removed the 2nd baffle and left the 1st baffle in.

Had a ride and it feels quite diferent, much much better.

Thanks ?

[WR_Dave]

I think you can ride without the tailpipe, but around here I need to be below 96 db to race and have a spark arrestor so it just finishes the pipe off better with a tailpipe. I found on my buddies bike that it sounds a bit better with the tailpipe in place. Anyone know what a YZF 450 tail pipe looks like?" There must be a totally different end plate on the muffler. WR Dave

[MKP]

Thank you WR Dave. ?

Now I see two options that should lead to the same result:

1) Leaving the 1st baffle IN and the tailpipe OUT.

2) Removing the 1st baffle and put a larger tail pipe.

Marco

[Dodjy]

Thank you WR Dave. ?

Now I see two options that should lead to the same result:

1) Leaving the 1st baffle IN and the tailpipe OUT.

2) Removing the 1st baffle and put a larger tail pipe.

Marco

Marco, a lot of people ride without the tail pipe, won't do any damage, except maybe get carbon around all the exits. Is best to have a tail pipe in as it helps get the exhaust cleanly away. If you haven't got a larger tail pipe, you'd be best off with none on. It's really easy to find a bit of 2mm stainless sheet (even mild steel is OK), shape it using drills, hacksaw and a file and weld a bit of pipe to it.

Mike, these mufflers are 05's they are aluminium outer oval shaped and a lot different to the 04 model. ?

[YamahaWR450FMike]

is there a modifcation for a 2004 WR450 stock pipe?

[WR_Dave]

Hi Mike, this is what I did to my earlier version WR muffler. WR Dave.

Subject: WR CDN. muffler mod

I cut 4" off of the end of the stock canadian muffler in the band saw( cut off saw would work too) Then I made the attaching piece out of 1/4" flat steel.

Basically I made a 1/4" thick donut that fits inside the stock WR muffler can and cut the inside out so the Honda XR 400 Competition spark arrestor would fit through it. I then welded the donut into the end of the can, fit the arrestor and marked the hole locations. Then remove the arrestor and drill and tap the marked hole locations for the correct size bolts. I made a gasket from some heavy heat resistant gasket material and bolted it all together and went riding. Don't forget to gut the muffler can(baffles and redirect pipes) before you weld the end peice in. I did that with a hammer and a sharp long chisel. I didn't need to rejet because I had already drilled a bunch of holes in the stock end of the muffler.This procedure basically gave me an approved spark arrester muffler that is nowhere near as loud as the stock YZF pipe . I will try to send a cut away picture of the pipe differences also so you can see what I cut out.This mod only cost me $50.00 CDN. but I did the work myself. Good Luck-----WR Dave.

[MKP]

WR Dave:

I've got it !!! ?

I'll work on a new tailpipe (35 mm ID).

Thanks for the savings ?

Marco

[pkcof]

awesome, this thread is really evolving and helping a lot of people along the way !!!

[pkcof]

Just finished the mods (all except the last baffle - closest to the header) and having a beer or two to celebrate. It sure helps the engine all the way across the rev range. The best thing is that it is now 'relatively' easy to tune to accommodate racing, club rides and legal requirements as they arise due to custom tail pipes and packing variations ... +/- spark arrestor options ... so far this has to be one of my (and a lot of my 450 mates) favourite threads !! " Cheers Dodjy "

[oberhemv]

This sounds great and makes me want to go out in garage and do it right now. I plan on removing the one baffle nearest the tail pipe and making a new tail pipe(35mm) as described. Question about the screen attached to the front of the tail pipe, do you guys reinstall or leave it out.

Thank you

Matt

[WR_Dave]

Around here we need to have the spark arrestor in place to ride and race, so the answer for me is yes we keep the arrestor screen in place. WR Dave.

[Kepy]

I made almost this same modification on my pipe few weeks ago. I left only the tail pipe and the spark arrestor in place however I cut off the tail pipe from the inside of the muffler.

http://i28.photobucket.com/albums/c202/Kepy/PICT1935.jpg

The muffler sounds very loud and high now and I want to get it more bassy, so the next step for me will be to remove the whole perforated plate from inside of the muffler shorten it in diameter and get much more packing into it.

As packing stuff I can truly recommend you to use a fire-fighting blanket. I use it for years and it works great. ?

...and the story go further... I ground the exaust lip to 45mm diameter and will rise the tail pipe accordingly.

http://i28.photobucket.com/albums/c202/Kepy/PICT1963.jpg

http://i28.photobucket.com/albums/c202/Kepy/PICT1962.jpg ?

[pkcof]

Hey Kepy, another fine modification you've added to an already impressive list - do you still have the option of a spark arrestor ? (and what's next?)

[Kepy]

Hey Kepy, another fine modification you've added to an already impressive list - do you still have the option of a spark arrestor ? (and what's next?)

Hello to Australia !

I'll use the spark arrestor for sure, cause I'll weld the 40-45mm pipe to the existing base...this base fits to the spark arrestor as these parts are original Yamaha ?

[WR_Dave]

Dodjy has been at it again refining his already impressive muffler. Good on ya mate---WR Dave.

I finished my muffler, here are the pics. I got hold of some 1mm perforated stainless sheet with 5 mm holes. I reckon 3 or 4mm would be better but this is all I could get. I got it from a mate who makes race mufflers and he reckons he has never had problems loosing the packing through the holes. I rolled it around a 35mm (1.5inch) tube by tacking it to the tube at each end and rolling it around while holding it in the vice. I then clamped it using vice grip pipe clamps and welded it, then removed the tube from inside. It fits perfectly into the header pipe and my 36mm tail pipe fits tightly into it at the other end. I welded a “C” shaped locating ring to the outside of the header end to stop it pushing into the header pipe any more. When I bolt up the tail pipe it clamps it all together. I packed the muffler with fiberglass muffler packing (had to remove the end plate again). I couldn’t use the standard spark arrestor so I have none at the moment. Sound wise – it’s hard to tell as I have only ridden up and down my road, It’s a bit quieter but it’s still quite loud. Power – also can’t tell yet, I will need to take it for a proper ride to see and check that the jetting is OK. I’ll let you know in a couple of weeks.

Regards Dodjy.

[Parrot]

What I did, I removed all the internals from the stock pipe so the aluminum outer case was left. Cut off all but the base. Put in a Big Gun Race core and packing. Pop riveted the base and screwed the outlet together. Added a flat spark arrestor. Sounds the same as my sons YZ pipe.

Bob

[ncmountainman]

Dodjy has been at it again refining his already impressive muffler. Good on ya mate---WR Dave.

looks like a powercore 4 ? i cut 3" off my pc 4 and opened up the chamber around the perforated centerpipe(basically run it with no packing and just the 1/2" blanket around the inside of the can) definately increased bottom end. the FMF engineer i spoke with agreed with the fact if you shorten the can you must open the chamber to enjoy the most bottom gains possible. and its not really any louder than before (definately different sounding) ?

[Dodjy]

Question about the screen attached to the front of the tail pipe, do you guys reinstall or leave it out.

Thank you

Matt

I left mine in but you can have it either way. If you don't need it, for legal reasons or to stop bushfires, leave it out.

[Kepy]

I left mine in but you can have it either way. If you don't need it, for legal reasons or to stop bushfires, leave it out.

I left mine too for less back fire and more bassy tune reason ?

[Kepy]

Dodjy has been at it again refining his already impressive muffler. Good on ya mate---WR Dave.

What you've done man is a must step for more bass. I'll make this same mod after my fellow which have a welder comes back from the ski holidays ?