05' Yamaha WR 450 Stock Exhaust ~ Exposed

[basicblues]

I am in the process of modifying an 05' WR stock exhaust and since a few guys are asking for photo's. Here's 4 pretty good photo's of the O5' exhaust to let you know what your dealing with.

The 1st photo is just a lay out of the parts. The 2nd is a photo of the empty silencer shell looking from the mid pipe/header end. The 3rd is a photo of the mesh baffle without the packing, silencer shell and end cap removed as looking directly inside from the back of exhaust. 4th photo shows a close up of the mesh baffle so you can see the 8 welds (4 more on the other side) that hold the 2 different sections inside.

To disassemble the silencer, you will need to drill out all 8 rivits where the mid pipe connects to the silencer. You do not need to drill the 2 rivits at the very end of exhaust unless you are planning on removing the plate that holds the spark arrester and exhaust tip in place.

In my little experiment to start, I plan to drill these inter sections out to have a straight through flow and use a PMB insert w/spark arrester screen cone and see what happens. I don't have a stock YZ pipe to look at, but it seems like this set up may be very similar while retaining the stock 05' WR look which I prefer.

[Dan_Lorenze]

Nice work..... ?

[trailriderjoe]

Yes, very nice work ?. Let us know how it works. After I got into mine and made my own PMB insert (cone type since PMB's wasn't out yet) I saw the restriction in the two inner pipes and thought that would be the next step. Just got concerned when I saw the type of rivet they were using! I have never seen that type. What's your plan for the replacements? Just use stainless large headed? with maybe a backup washer?

Glad to see someone else willing to play with the stock stuff to make it work, rather than just pitching it and buying new. It's almost funner this way ?

[trailriderjoe]

Bump

Survey says.........

[basicblues]

I saw the restriction in the two inner pipes and thought that would be the next step. Just got concerned when I saw the type of rivet they were using! I have never seen that type. What's your plan for the replacements? Just use stainless large headed? with maybe a backup washer?

Glad to see someone else willing to play with the stock stuff to make it work, rather than just pitching it and buying new. It's almost funner this way ?

Well I've been slammed at work this past week so I haven't had a chance to proceed with my 05 exhaust modification project. Weather forcast this weekend is 2 solid days of rain so hopefully I'll have time to find out more.

However I have pecked around with the inner pipes lightly and it looks like it's going to be quite challenging to get these out.

I haven't seen rivits like these either. I went to Lowe's looking for new rivits, they had aluminum and steel rivits. I'd like to find a good stainless steel rivet. You really can't fit a nut on the inside of the shield without tack welding a nut otherwise stainless bolts & nuts would probably be the best choice since you could easily take the silencer apart to repack as necessary.

Stay tuned...

[basicblues]

Finally here's the photo's of my 05' exhaust mod I started a few weeks ago. For those just tuning in to this thread, check out the 4 photo's at the start of this thread showing the 05 WR stock exhaust unassembled.

Yamaha never intended for anyone to take apart the 05 exhaust. The baffles inside the silencer sleeve took a little trial and error for me to figure out how to get them out without damaging the silencer. (1st) I tried to drill out the welds which would probably work but was too time consuming. (2nd) I applied heat thinking I could knock with welds loose. I thought of using a cutting torch which would certainly work but I was afraid the cut would live melted metal. The sleeve is easy to bend and must stay in it's original shape to be able to slid the baffles out. (3rd) I used a dremel and several a cut-off wheels to cut the welds out. This didn't take too long and left little "windows" in the silencer sleeve.

Some TT'er posted "this is where your problems begin with the 05' exhaust". Here's what the problem looks like. The 2 baffles are placed just like they are welded inside. No wonder the exhaust restricted.

I was concerned about the "windows" in the silencer sleeve and the possibility of an exhaust hotspot which may burn through the outer sleeve. I'd picked up a mig welder at a yard sale over a year ago but never have used it. So, I decided to see if I could weld the "windows" back in place, which worked great. This step is probably overkill and probably not necessary. If someone wants to do this mod, I would consider just using some automotive exhaust tape to cover the "windows".

Here's a photo shot of the inside of the silencer sleeve after the baffles were removed and "windows" back in place. This is as "free flowing" as it gets.

Of course the "pea shooter insert" is gone and a PMB insert installed. It probably doesn't matter that much but I decided I wanted a cone shaped spark arrestor inside of that stock buttplug type. The PMB insert is flanged out on the end and I cut and shaped the cone spark arrestor to fit and welded it in place.

All that's left to do now was to reassemble and install. I could only find aluminum or steel rivits at the local hardware store and Lowe's. I wanted to use stainless steel rivits because the aluminum rivits may not be strong enough and the steel rivits would probably rust. I found a industrial supply store (Fastenal) and found stainless steel rivits. The only thing I had to do extra on my 03' WR was trim the rear fender exhaust slot slightly to accept the 05' exhaust. Last photo is just a photo of the pipe back together and installed on the bike.

[xcracer123]

WOW!! You sure have put a lot of work in to that thing! I didn't realize that it would be that much work! Guess I'll be busy with that for a while. Thanks for all the great pics and description though.

I'll have plenty of time to tinker since I re injured my knee today trying to ride too early. It was feeling pretty good so I thought I'd go out with some friends for an easy trail ride. So much for my knee not hurting anymore. What an idiot I am. Looks like I'll be under the knife before too long and not on the bike the rest of the year. Sucks for sure. Later......

[Dunlop]

How much louder is it?

[basicblues]

How much louder is it?

I was running the stock 03' pipe with GYT-R inserts with the 3 tubes removed. So I've been use to what that sounds like. I thought the modified 05' pipe would sound way louder but if it's any louder at all it isn't much. I only rode the bike for about 3 minutes before heading to my computer to post photo's. The sound is different, I think the tone may be higher but I'll need to spend more time on the bike to evaluate but the pipe does have a good sound. I've never been sound checked here and don't have access to a meter, so I don't know the exact sound db's.