Modified stock pipe saves big $$$

[WR_Dave]

Dodjy in Australia sent me these pics and very detailed drawings of how he modified his stock muffler. Saves big money over buying a new muffler for us frugal WR owners. Just like the Free mods that make the bike better. This will help the WR's rip. Thanks Dodjy!!--- WR Dave http://img.photobucket.com/albums/v234/WR_Dave/35mmTPfit2.jpg http://img.photobucket.com/albums/v234/WR_Dave/35mmtailpipe2.jpg http://img.photobucket.com/albums/v234/WR_Dave/insidemuffler2.jpg http://img.photobucket.com/albums/v234/WR_Dave/tubesideview2.jpg http://img.photobucket.com/albums/v234/WR_Dave/layout2.jpg

Attached is the info you need, feel free to post on the forum if you know how. There’s 2 rivets holding the end on the muffler not 4 (I forgot), I just replaced them with aluminium rivets instead of the stainless ones. Had no worries yet. The 29mm tail pipe just fits through the hole in the end cap while the 35mm version fits snug into the lip on the inside of the end cap. Both have heaps less restriction than the stock one and they only took me 30 minutes to make and cost nothing. I still run the stock spark arrestor. I reckon the perforated pipe and packing will improve it as it will effectively add length to the exhaust so should improve low to mid speed. As it stands now it is still the same length as stock but has more power everywhere. Just remember if you cut the 2nd (front) baffle out there’s no going back. With the 1st baffle (rear one) removed, the bike will still be reasonably quiet, especially with the stock tail pipe so it’s worth doing it in stages if you can.

Regards Dodjy.

[OneToGo]

Holy Cr## good work dodjy!!

Thanks for passing along the info and pics as well....- looks like major surgery!

If you could yank those baffles out easily then Yamaha would have no need to market any other aftermarket pipes - we could make our own!! ?

From the drawings, it looks like you "just" need a 45 mm full length perforated pipe (surrrounded by packing), and you in effect have a race muffler!

?

Nice one

Colin

[rich1167]

I removed the 2nd baffle and punched big holes in the 1st one. The bike rips. But is a little louder, as you would expect. Over all I am happy with bikes performance after this mod and will not buy an aftermarket pipe.

[pkcof]

"Excellent" work Dodjy ... i can see that this is going to be a popular thread and i'm going to start on my exhaust tomorrow !!!

[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. ?

[WR_Dave]

I think using a much larger tail pipe section like Dodjy describes in his drawing will help the tone quite a bit on your modification. The small tail pipe is still killing your opened up muffler. My .02--- WR Dave

[Kepy]

I think using a much larger tail pipe section like Dodjy describes in his drawing will help the tone quite a bit on your modification. The small tail pipe is still killing your opened up muffler. My .02--- WR Dave

will try it next days. Hopefully I'll get a bit more bass (no bass no fun ? )

[Dodjy]

"Excellent" work Dodjy ... i can see that this is going to be a popular thread and i'm going to start on my exhaust tomorrow !!!

No worries, but if your worried about being too noisy, you might want to leave the front baffle in (with the single pipe through it) or do it in stages as there's no going back, apart from bolting your standard tail pipe back on. We ride in the bush where there's no one for miles around to bother. It's a cheap mod (cost me nothing) and you get to keep the stock pipe which I reckon looks better than the aftermarket ones anyway. Here your looking at about $500 to $800 for an aftermarket pipe. Thats quite a few sets of tires which will make you heaps faster than a shiny new pipe. When I add the length of perforated pipe and pack the muffler I'll let you know how how it goes.

[pkcof]

hey Dodjy ... excellent work that you've done on the standard 'piece of s#it' exhaust on the '05 ... ?

i know that it's not easy to describe here in detail, but is it possible to do the baffle modifications and still leave the final plate intact - the one with the 2 rivets (top and bottom) that holds the spark arrestor in place with the 4 bolts (or can it be removed in order to do the other mods and then replace it?) Then i can rivet (aluminum?) the end tip back on and it will still look stock

[WR_Dave]

Note the second picture in my post at the top.Dodjy said that he remove the rivets and very carefully, so you don't bend it, remove the spark arrestor mount plate and do the pipe mods. Then just reinstall and re-rivet the spark arrestor mount plate and hang on. WR Dave. ?

[pkcof]

Note the second picture in my post at the top.Dodjy said that he remove the rivets and very carefully, so you don't bend it, remove the spark arrestor mount plate and do the pipe mods. Then just reinstall and re-rivet the spark arrestor mount plate and hang on. WR Dave.

Thanks WR Dave, i thought as much ? ... it's just that i removed the rivets, re-drilled all of the holes slightly so that there's no 'lip' holding it in (is it pressed in or something?) but damn - i'm trying not to damage the thing ... any suggestions on how to remove it reasonably intact? ?

[Dodjy]

Thanks WR Dave, i thought as much ? ... it's just that i removed the rivets, re-drilled all of the holes slightly so that there's no 'lip' holding it in (is it pressed in or something?) but damn - i'm trying not to damage the thing ... any suggestions on how to remove it reasonably intact? ?

I didn't re-drill mine, so I could keep the same size hole in it. It took a while to get it moving but once it started it kept on comming. I used a dodjy version of a slide hammer. I didn't have one so I used a Z shaped arm off one of my big pullers and a hammer to knock it out. You just gota be carefull not to bend it too much. I just knocked it back into shape. I think it's best to use the area where the nuts are welded to the plate as it is the strongets point to hit against. If your got a slide hammer you could use the bolt holes to pull it out.

[Guest Joe Schmo]

How do you get the baffles out?

They're tack welded in 4 spots. Do you drill it, cut it or chisel it out?

[WR_Dave]

When I get home from work I'll edit Dodgy's instructions into the first post. Not thinking, ? I should have done it in the first place, but yes he used drill bits and cold chisels to remove the offending tack welds. WR Dave.

[Dodjy]

How do you get the baffles out?

They're tack welded in 4 spots. Do you drill it, cut it or chisel it out?

A drill, sharp cold chisel and a hammer. You can use a die grinder (dremel) to clean it up if you want.

[MKP]

I did my homework yesterday removing the 2nd Baffle. ?

Took several hours, mainly used a Dremel a hammer and a chisel. It was hard.

I didn´t remove the 1st Baffle (too tire) but didn't put back the tail pipe.

Now I have more top end, and is not louder than my old '99 YZ400F.

Why using the tail pipe ? (No sound restriction here) ?

Thank you (nice saving $$$)

[WR_Dave]

Instructions now in the first post of this thread. WR Dave.

[bluebike1999]

Nice job dodjy. i did my 400 exhaust myself in a similar fashion.

this was stock 23mm id tailpipe

http://img.photobucket.com/albums/v696/bluebike1999/pipe_0792.jpg

99 have a sealed system and had to cut off end with angle grinder, drill out the tailpipe with 1/8 bit, then replaced it with 38mm id exhuast plus drilled two 10mm holes through the baffle inside.

http://img.photobucket.com/albums/v696/bluebike1999/DSC00061.jpg

then got pipe all mig'd back up at local muffler shop. $30 all up.

http://img.photobucket.com/albums/v696/bluebike1999/DSC00069.jpg

didnt want to go too far so to avoid having to rejet.

not too loud, starts easier(i believe) feels good.

saved a heap of $$$ but still heavy.

[YamahaWR450FMike]

Dodjy in Australia sent me these pics and very detailed drawings of how he modified his stock muffler. Saves big money over buying a new muffler for us frugal WR owners. Just like the Free mods that make the bike better. This will help the WR's rip. Thanks Dodjy!!--- WR Dave http://img.photobucket.com/albums/v234/WR_Dave/35mmTPfit2.jpg http://img.photobucket.com/albums/v234/WR_Dave/35mmtailpipe2.jpg http://img.photobucket.com/albums/v234/WR_Dave/insidemuffler2.jpg http://img.photobucket.com/albums/v234/WR_Dave/tubesideview2.jpg http://img.photobucket.com/albums/v234/WR_Dave/layout2.jpg

That's funny, my 2004 WR450 stock pipe looks nothing like that one. Mine is very round

[Guest Joe Schmo]

Well fark me !! ?

I finally got one baffle out (the one with 2 pipes through it).

I felt like it took forever. ? The plate that the spark arrestor bolts to just wouldn't come out so i had to pull the guts out through it.

I think i'll just leave it at that for now. I'll have a ride on the weekend and see how it goes. I had to pull the 2 pipes through it seperately. Together, they wouldn't fit through.