Modified stock pipe saves big $$$


140 replies to this topic
  • Demo_Slug

Posted June 09, 2008 - 10:06 AM

#81

This is my home-made 31.8OD x 29mm ID insert:
Posted Image


Just wondering what the thought process was on chossing the length of this tube? does longer miake it quiter or make the sound deeper?

  • WR450FGreg

Posted June 09, 2008 - 12:08 PM

#82

Just wondering what the thought process was on chossing the length of this tube? does longer miake it quiter or make the sound deeper?


Demo_Slug,

Obviously the outlet half is governed by the distance from the second baffle to the end-cone.

For the inlet half I looked at:
a) The stock unit and how it related to the spark arrestor (which I wanted to retain).
:thumbsup: The aftermarket units made by various people and companies.

The stock unit began very close to the spark arrestor, meaning that the exhaust gases had to turn quite a sharp corner in order to get around and through the spark arrestor then into the tailpipe and out. This I didn't like.
Some aftermarket units had no inlet side at all, leaving no scope for tuning. This I didn't like either.

So I decided to begin my tube about 20 - 25mm (I can't recall the exact distance, I have it written down somewhere in my workshop) from the end cap of the spark arrestor to give the gases a more direct path out. This was a bit of a "hit and miss" process and thankfully it appears to have been a "hit"!

I left it long because I wanted scope for my friends and I (I made a few of them for my mates too) to be able to trim sections off it in stages if and when one of us eventually got our bike onto a dyno, to see what difference it made.

Tone: Sound-wise I can't really comment on the tone having not had the bike running beside one fitted with the stock insert. Based on my limited musical knowledge it should sound a bit deeper I guess; bigger diameter, lower frequency, slower moving sound waves, etc.

Volume: I asked my girlfriend to listen to the bike running before and after I fitted the insert and we both agree that it is slightly louder, but there isn't much in it at all compared to the stocker. Without a sound meter this is very speculative!

This thing cost me next to nothing, was fun to make, and it works!

Posted Image

  • Demo_Slug

Posted June 09, 2008 - 12:21 PM

#83

WR450FGreg,
thanks I was just wondering. I have the GYTR insert... my buddy has the PMB insert. my GYTR has no "scope" on the inlet side. but the PMB insert does. :thumbsup: the PMB also has a slightly larger OD, it barely fits into the tail piece, while the GYTR has a small gap around it.

it just has intrigued me with the 2 different approaches.

  • gasser250

Posted June 16, 2008 - 06:10 AM

#84

We just did this mod to a mate's 05 wr250 this weekend. Finished it off with a 35mm end cap. It's definitely a lot faster and a lot louder. But it does sound quite different to my brother's 03 wr250 with an FMF "power bomb" system.

The wierd thing we found though was that the needle on the 05 wasn't adjustable as they are in the 03 and as shown in the manual. We put the carb back together and found that after normal wr warmup splutter it actually still ran spot on... mystery.

Thanks though... his bike doesn't sound like a friggen hedge trimmer anymore.

  • WR450FGreg

Posted June 23, 2008 - 12:51 AM

#85

I am currently making a few of these (about 12) to sell on eBay soon .....

Posted Image

I might make 3 versions I think:
1. Just like the photo, so you can tune (cut the inlet side) to your own preference.
2. Short (no inlet side at all)
3. Low-noise (slightly less power, but at least quieter than 1 and 2 above.)

What do you think ... will they sell? I intend to sell them for around $US65 each.

Greg

  • Demo_Slug

Posted June 23, 2008 - 10:42 AM

#86

I am currently making a few of these (about 12) to sell on eBay soon .....

Posted Image

I might make 3 versions I think:
1. Just like the photo, so you can tune (cut the inlet side) to your own preference.
2. Short (no inlet side at all)
3. Low-noise (slightly less power, but at least quieter than 1 and 2 above.)

What do you think ... will they sell? I intend to sell them for around $US65 each.

Greg


How would your product differentiate itself from what is currently on the market?

  • WR450FGreg

Posted June 23, 2008 - 12:05 PM

#87

How would your product differentiate itself from what is currently on the market?


Demo-Slug,

Not much except the fact that there are 3 versions to choose from and(depending on what version you choose) mine will differ:

1. Just like the photo, so you can tune (cut the inlet side) to your own preference.
2. Short (no inlet side at all)
3. Low-noise (slightly less power, but at least quieter than 1 and 2 above.)

I will also include jetting advice and how to modify your existing muffler to get the most from the new tailpiece.
(Ok, everyone here in ThumperTalk knows how to do it, but what about the other guys who don't?)

These things have been very well received by my friends who have tried one, so I will make a few for others to try.

Greg

  • coloradobrad

Posted September 17, 2008 - 09:26 AM

#88

Hi Folks-

I read this great thread and then removed both baffles and the tail-pipe. I left the s/a installed. It really woke up the bike. I mean it was night and day difference. The downside... It's loud as hell. It sound tested at 105dB@4500rpm.

I installed a Leo Vince X3 i picked up on craigslist on the super cheap :excuseme: It's prob the nicest pipe I've ever installed. Much nicer than the FMF Q on my 03. Anway, its much quieter than my gutted stock pipe (has ~94db & ~102db inserts) and the bike has even more power now. The X3 is deeper sounding and much more refined.

This mod is great for the frugal and those who like to tinker. Personally I like my X3 about 5X better. If I were to keep the gutted stocker, I would def build a perforated tube with a baffle and pack it.

  • WR450FGreg

Posted October 11, 2008 - 12:42 AM

#89

.
Guys,

For reference..... this is what a complete '08 WR450F muffler looks like when you drill the rivets out and pull it apart....
Posted Image

Those of us wanting to remove the two baffles (walls with the holes/tubes) will find it pretty easy to do once you pull it apart like this.
You can grind the welds away with an angle grinder and the baffles will come out easily and neatly.

I've made mine breath free-er yet again (without removing the baffles) by drilling more holes and enlargeing others in the baffles to compliment the YZ450F header pipe I'll be fitting this week.
I actually have the whole YZ450F system but would prefer to retain the quieter WR450F muffler (at least I hope it will still be quieter now that I've drilled it some more!) if possible.

Pics to come.

Greg

  • WR450FGreg

Posted October 18, 2008 - 08:01 PM

#90

.

I scored a complete '08 YZ450F exhaust off eBay for $Aus200 (about $US140 or so). I don't intend to use the muffler because I suspect it will be quite loud. Besides, i like my bike to have a "stock" look.

I have fitted the header pipe, which is a larger diameter than the stock WR450F item (BTW, the extra hose clamps are there because that's where I store them) .....
Posted Image

I've pressed the stock tail-cone out to take a bigger diameter insert. This shot shows the size, that's one of my 29mm ID inserts in there, not the OEM one ....
Posted Image


I haven't gotten around to making a 38mm ID insert yet so I decided to drill a series of 6mm diam holes around the 29mm one to make the oriface size geometrically the same as for a 38mm insert for the time being.....
Posted Image

I also drilled each baffle inside the muffler to maintain a 43mm diam effective flow area, rather than the stocker's much smaller one. So, right from the head to the tail-pipe the system is 43mm ID, at the very end it reduces to 38mm, similarly to aftermarket systems such as White Power (I did my homework.)

Result?
Definate increase in bottom end and midrange acceleration. Can't tell any difference in top end.
Yes, it is louder than stock, but not excessively so. It sounds f....g awesome though! MUCH deeper and throatier

Comparing the '08 YZ450F system to the '08 WR450F one:

Weight of WR muffler: 3380 grams
Weight of YZ muffler: 2450 grams

Weight of White Bros WR muffler: 2900 grams
No White Bros header available to weigh.

Weight of WR header: 668 grams
Weight of YZ header: 562 grams

OD of WR header: 39mm
OD of YZ header: 43-46mm


Jetting?
The bike was a little rich before this latest modification, so far the jetting seems fine but i haven't checked the plug to make sure. The throttle response is certainly still there and it revs fine everywhere.

I've seen claims elsewhere in this forum that the '07/'08 YZ450F exhaust won't fit the '07/'08 WR450F. It does.

I've also seen claims that all you need is the OEM '07/'08 YZ450F header/muffler seal to fit an '07/'08 YZ header to an '07/'08 WR muffler. This isn't exactly correct. Yes, you need the seal, but you have to un-wind it and cut it to give a single layer of it, combined with some high temperature silicon. The muffler's "flange" size is slightly smaller on the WR than the YZ and won't accomodate the full seal thickness.
(The OEM YZ seal is like copper fabric tape, wrapped around the header two or three times to achieve the thickness.)

Greg

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  • speedcomm

Posted October 20, 2008 - 02:02 AM

#91

I was going to ask about the hoseclamps as I looked at the pic before reading the text :D

  • WR450FGreg

Posted October 25, 2008 - 12:45 AM

#92

.

This is as big as you can go with cold-pressing an '07/'08 WR450F muffler end cone out to take a bigger tailpipe insert.....

Mine was just beginning to split a little internally at this diameter.
Realistically you wouldn't want to go any bigger anyway, you need to maintain some back-pressure within the system.

Greg

Posted Image

  • 05-WR450F

Posted November 18, 2008 - 08:48 AM

#93

Opening up this again...

I am in the process of modifying my stock 05 exhaust. Removed the entire core and replacing it with Moose packing and a 2.5" perforated stainless pipe. I also shorted the whole can by 3". I am expecting it to be quite loud so I am going to use my Pro-Moto insert to choke it down a bit at the end.

How did you guys go about cold-pressing the end cap in case I want to make a bigger outlet pipe?

I will post some pics when I get it all done.

  • Dominion

Posted November 18, 2008 - 11:06 AM

#94

So this is all butt dyno or is there a way to quantify the results? Anyone have access to a bike dyno to find out the power increases over stock?

  • 05-WR450F

Posted November 19, 2008 - 03:24 AM

#95

butt dyno for sure. doing this to save money but i'm sure the results are pretty obvious; more power and better sound.

  • WR_Dave

Posted November 19, 2008 - 05:59 AM

#96

:thumbsup: Don't forget that there may be some psychological horsepower mixed in there too! Seriously, like 05-WR450F stated, this is for the budget concious rider , people who still have lots of money or credit can opt for the store bought systems. No one said this was better than the aftermarket systems, just cheaper. :moon: WR Dave.

  • WR450FGreg

Posted November 19, 2008 - 11:09 AM

#97

How did you guys go about cold-pressing the end cap in case I want to make a bigger outlet pipe?


You need to turn up internal and external press tools (basically a tube for the outside and a solid boss for the inside) to suit your application then use a bearing press carefully !

It's easier to just make a larger diameter tailpipe. One that just fits either inside or outside the outlet itself.
It won't be as big an outlet as the pressing method but a lot simpler.

Greg

  • ch_250

Posted November 19, 2008 - 08:27 PM

#98

i have a canadian model and the end cap is welded on as has been previously shown here, but my question is how deep are the baffles into the can? i plan to cut the end off and fix it up nice, but how far forward from the back can i cut it without cutting the baffles?

  • WR_Dave

Posted November 19, 2008 - 08:54 PM

#99

You can see where the baffles are by checking for the spot welds on the sealed Canadian can. WR Dave

  • ch_250

Posted November 19, 2008 - 09:09 PM


sweet, cant wait to start it




 
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