08 YZ450f Exhaust

[WILLIAMS37]

Okay, So a while back I remember seeing people cut out one of the cones inside the 08 yz450f exhaust. I never really thought about it until the other day when I bought pop rivets for another project. So I'd be able to disassemble the pipe and get it back together. Does anyone know the exact process? Or have pics? Also, what about the power gains? Thanks in advance.

[grayracer513]

https://www.thumpertalk.com/forum/search.php?f=21

[SXP]

https://www.thumpertalk.com/forum/search.php?f=21

Aww Gray, that was cold. I clicked on the link with great expectations of finding a blow-by-blow account of how to mod the muffler

[WILLIAMS37]

https://www.thumpertalk.com/forum/search.php?f=21

I always feel so dumb when I get told to search:bonk: . In my defense though, A lot of threads found when I search are completely irrelevant to what I'm looking for most of the time.

[grayracer513]

That particular subject has come up a number of times, though, and recently. I believe the rearmost cone is removed. There's a cutaway HERE

Use the search function with keywords, "muffler" with and without "'08", "08", or "2008" and you'll come up with several threads on the matter. As far as I know only one or two claim to have done anything with it, and provided scant detail.

[erickdj]

Well, we've heard many different stories about the matter. Some say that removing the rearmost cone ruins the muffler and provides no real benefit, while others say that it's the way to go, or at least that's the implied message. Well, looking at the pictures I"m getting the idea that maybe if said tube is to be perforated, along with adding a spark arrestor, then a reasonable compromise can be reached of noise/performance. A second theory would be to remove that cone and add the spark arrestor. I have a spare stock 08 exhaust boxed up, plus a new spark arrestor screen. One of these days I might take on the project of modifying the "shorty"

[mc1hd]

I just installed a pro moto billet spark arrestor on 09 yz450 stock silencer. Tried it with the insert they provide and its loose inside, can here it rattle. After removing the insert there is more noise and seat of the pants feel it runs better. This is with the screen installed.

[Gus801]

ol post i know.

want to note my findings .

I just removed both cones in my 08 ' shorty muffler. I re jetted it fat, one riding trip, before the exhaust mod .

Is there a low end difference ? YES good ( it pulls easier out of a higher gear roll )

Is it louder ? YES .(not any louder than my buds stock 06' yz)

does it sound like crap ? NOPE .( same rhythm just faster, deeper thump )

The best way to describe the feel of the bike after is..." it really woke up ".... pure cliche,( I read that all the time) but it is true.

I rode my bike stock for 1 year before hacking the pipe , waited untill I was used to the bike before changing things, modifing the stock muffler before buying a new aftermarket one is well worth the time spent . FREE .

I didnt follow anybodys "how to". I just removed the welds out of both cones and left the packing, tube ,etc in place . dont know what everybody else is doing but I suppose the same thing I did .

I dont think I will buy another pipe unless this one gets smashed.

Very happy with the results .

Cheers !

[Yzflier977]

I personally did this mod to my 2009 450 a few weeks ago and love the feel of the power delivery now. To describe it I would say it has more snap of the bottom end, just doesn't feel as sluggish as it was with the cones. As far as the process on how to do it, that's pretty simple. Notice I said simple and not easy. It's not that difficult, but it isn't that easy either. Just disassemble the canister like you would be replacing the packing. Make sure you have the proper rivets to go back before you start this. If you use ones that are just long enough they'll break fairly soon. You'll need a rivet gun which you can get a cheap one at most auto parts store for under $20. The rivets you can get at a home improvement store. Anyway remove the main canister and the end cap by drilling out the rivets that hold it all together. If the perforated tube has any packing residue clean that off and make sure none of the holes are plugged up. Wire brush or wire wheel on a grinder works well. You'll clearly see the cones on the inside. There's one toward the end and one toward the front. Both are held inside there with 3 spot welds. Those spot welds are what you'll need to drill out and then the cone will come out. If you have access to a cutting torch it'll make life much easier because these spot welds are not easy to drill out. From there it's just repacking it and reinstall it all together This basically makes it a free flowing muffler with the stock shorty canister. I did need to richer it up a little which I did with a different needle and a clip change for my location. That's it. Costs you some time and packing material and that's about it. Hope this helps.

[Gus801]

I found a used spark arrestor end cap for a 06' for 30 bux . Installed it after some work to the can. turned out good .