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JMundy

2012+ Yoshimura RS4 Question

18 posts in this topic

I am curious if the spark arrestor in the rs4 for the WR450 is removable and what is everyones overall thought on the exhaust system

 

Im thinking of taking a chance and trying a Yoshi RS4 full system on my 2007 WR450.  I know its listed for the 2012+ but it sounds like all the 07+ years are swappable on exhaust systems for the WR.   Dr.D even lists thier system for 07-15 WR450.  I just dont like how far back the RS2 system sticks out the back like the stock WR exhaust does.

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It's loud (100db)

Stock WR is about 86 db

Pea Shooter removed is about 90 db.

The end cap is Carbon fiber, so don't drop down on it.

 

The RS2 is more durable (SS endcap, no titanium), quieter, and has a longer header pipe, for more low rpm torque.

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I went ahead and bought the Yoshimura RS-4 pipe for my bike.  Decided to post up some comparison pics incase anyone else in interested in it as I never found any information when I was searching.

 

First off yes, the 2012+ RS-4 exhaust will work on a 2007 WR450.   Also, this is one well build exhaust.  The fit and quality are very nice, what I would expect from Yoshimura.  It bolted right up like I was expecting / hoping.  Its faily light, much lighter than stock wr system, very similar to yz exhaust.  Header of the yoshi system is almost as light as the titanium yz header.   I love the fact that the header on the yoshi has the heat guard that goes so much further towards the front.  Ive dented the yz pipe right in that area and hoping with the guard there and the stronger SS over Ti I will no longer have any issues.   I do wish the RS4 didnt stick out so far out the number plate.  That was one thing I loved about the yz exhaust, tucked away and clean looking.  That being said, it doesnt stick out nearly as far as the stock wr system.   RS4 system comes with a spark arrestor already installed, and does not come with the insert to remove it.  I still need to contact Yoshi and see if one can be purchased with how the exhaust exits at an angle.   The exhaust is not that loud, atleast when compared to the 08 yz system.  it sounds very similar on a idle, and a little bit cleaner/crisper in mid throttle.   Overall I am very pleased with it

 

So everyone really just wants to see pictures so here it is

 

2015-06-18%2018.12.15.jpg

 

2015-06-18%2018.12.22.jpg

 

2015-06-18%2018.12.27.jpg

 

2015-06-18%2018.12.34.jpg

 

2015-06-18%2018.15.47.jpg

 

Comparisons against the stock WR exhaust and a stock 08 YZ exhaust

 

2015-06-18%2017.39.50-1.jpg

 

Exhaust Pipe Diamaters (top left is yz, top right is yoshi, bottom is wr)

 

2015-06-18%2017.40.26.jpg

 

Header Comparison (top to bottom - yz,wr,yoshi)

 

2015-06-18%2017.41.37.jpg

 

Header Pipe Comparison (top is yz, bottom left is yoshi, bottom right is wr)

 

2015-06-18%2017.41.06.jpg

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I dont know where you heard stainless is tougher than titanium alloys?

The opposite is true.

I hate the rs4 on myne personally, looks flashy from the outside but the build quality is not evident otherwise. The mid pipe mount cracked and tore off on myne. When i repacked i found the end cap wasnt properly drilled so the perforated pipe is loose and rattles after a while.

I've gone back to a 06 yz muffler, much lighter, quieter and better built. For the same power output.

My experience with any of the American muffler brands has not been good. If i get another aftermarket i'll try the european pipes.

Edited by xy500

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I dont know where you heard stainless is tougher than titanium alloys?

The opposite is true.

I hate the rs4 on myne personally, looks flashy from the outside but the build quality is not evident otherwise. The mid pipe mount cracked and tore off on myne. When i repacked i found the end cap wasnt properly drilled so the perforated pipe is loose and rattles after a while.

I've gone back to a 06 yz muffler, much lighter, quieter and better built. For the same power output.

My experience with any of the American muffler brands has not been good. If i get another aftermarket i'll try the european pipes.

 

Theorettically true

 

In practice, they are too brittle to be practical.

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Theorettically true

In practice, they are too brittle to be practical.

What is too brittle to be practical?

304 SS - 515MPa and brittle

Ti alloy 1000 MPa and tough

"Titanium alloys ... have very high tensile strength and toughness (even at extreme temperatures)"

So Ti alloys are theoretically and practically stronger and tougher than all grades of SS. As well as having other favourable properties.

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What is too brittle to be practical?

304 SS - 515MPa and brittle

Ti alloy 1000 MPa and tough

"Titanium alloys ... have very high tensile strength and toughness (even at extreme temperatures)"

So Ti alloys are theoretically and practically stronger and tougher than all grades of SS. As well as having other favourable properties.

 

Obviously, you have never owned a Titainum pipe.

They don't dent, they crack

They don't bend, they split or collapse

Light and fragile tubing.

 

That is why all the SX pros use a second layer of titanium on the outside of their headers, as a couple of well placed rocks will take it out.

..and that is the premium Ti metal, not  the consumer crap we get.

 

 
Not so with heavier SS, even at the same guage.

 

That is also why none of the motor mounts, mount spacers, wrist pins, rings, circlips, spokes, etc etc, are ever made from Ti on a Pro level bike.

Too fragile, and not flexible enough. They use alminum or steel alloys. Even Carbon Fiber is superior for most applications.

 

If you have ever overtightened a Ti bolt and heard it crack, ever fallen on a Ti Silencer can, ever had your buddies rear wheel spit a rock and split your CRFR header in half, you'd understand.

Edited by KRANNIE

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Obviously you're an opinionated and kranky old man, with no experience in materials selection. No such thing as consumer grade ti, its grade 5 or not. Composition is composition.

I have owned both, and others. Titanium is far tougher and far less prone to cracking. Its hilarious you suggest CF as being tougher, as it is universally accepted as being a particularly brittle material.

If you managed to crack a ti header you would have destroyed completely a ss header.

I have two old headers, one ss one ti. I can swing a hammer at both and guess which one dents and which doesnt?

Thats the definition of toughness.

All practical experience industry has with these two materials disagrees with you.

Edited by xy500

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Dude, you just don't get it.

 

Thousands of posts on the subject of cracking Titanium head pipes, and not off road bikes either.

 

https://www.google.com/search?site=&source=hp&q=Titanium+header+cracking&oq=Titanium+header+cracking&gs_l=hp.3...726.6830.0.7252.35.29.5.0.0.0.129.2216.27j2.29.0.cfr.2..0...1.1.64.hp..4.31.2015.0.me3-dgRO76k

 

No top fuel dragster in the world uses Titanium headers.....because the crack with vibration, unless they are made so thick they are no longer lighter, and are then 50 times more expensive.

 

No F1 car uses hardly any Titanium other than fasteners....they use Carbon Fiber and Steel, because they  flex.

 

All the 70's Suzuki and Husqvarna Ti factory bike frames all cracked eventually.....and not at the welds either.

 

The advantage of Ti is it's strength to weight ratio, not it's superior strength.  It's just not stronger, at all. 

The requirement of microcellular manangment during the creating of the alloy is so critical, that only three companies on earth do it correctly....all are areospace providers.

 

The Ti you and I see is pretty crappy stuff.........

 

  • Titanium has a lower (approximately 50% less) modulus of elasticity than stainless steel.  A lower modulus of elasticity means that titanium is significantly less stiff than steel
  • Stainless steel is approximately 10 times stiffer.
  •  

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In all my experience with Ti vs SS in purely a motorsports application, SS always lasts and is more durable.  Yes Ti is much lighter and is strong, but heavier SS just seems to be more resistant to dents, breaks and cracks.   

 

Just a guess as I do not deal with metallurgy as a profession, but perhaps with multiple heat cycles or the fact that when it is warm, perhaps then Ti becomes more brittle than SS.  Metal does act differently when heated compared to cool

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My WR  has TI valves in the motor and they seem to hold up just fine.

 

The TI headpipes have issues because they're thin not because they're TI.

 

Stainless is a lot cheaper and easier to weld.

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You guys need to admit you have NFI about materials.

Pure titanium, and grade 5 titanium alloy have vastly different properties. Googling Ti isnt going to help you here lol

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My WR has TI valves in the motor and they seem to hold up just fine.

The TI headpipes have issues because they're thin not because they're TI.

Stainless is a lot cheaper and easier to weld.

Exactly.

Titanium alloy exhausts run vastly thinner wall section than equivalent. AS IT IS MUCH STRONGER & TOUGHER.

Noobs should just keep quiet instead of spreading misinformation.

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ok, just to be a dick now that XY500 isnt apperantly listening to what I said.....

 

Never once did I say I have any metallurgy degree or use it in a professional matter, i even went out of my way to say I didnt.

 

Your arguement on pure Ti vs Grade 5 isnt going to help you here either.  I (and I doubt you) have no damn clue what class Ti is used in any part, be it the header or Valves.

 

The arguement being made that titanium headpipes are not weaker, they are just thinner.  Come on, this is simple cause and action.  Because all the Ti headpipes are thinner, therefor they are weaker and bend / break easier.  You kinda just walked back on your own arguement that Ti headpipes are stronger than SS, but you are agreeing that  the Ti headpipes have issues because they are thinner.

 

Seriously, just quit trolling and name calling people, you have brought no useful information to this thread

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You guys need to admit you have NFI about materials.

Pure titanium, and grade 5 titanium alloy have vastly different properties. Googling Ti isnt going to help you here lol

 

You keep reinforcing your opinion which has already been stated.

 

...but your explanation is still wrong, so get over it.

 

Titanium has a low coefficeint of Plasticity, compared to steel alloys.  

 

That is what makes it brittle when used in a sheet or tube or tab.

 

It's streght to WEIGHT ratio is higher, but that does not have anything to do with Plasticity, it's ability to deflect, or be deformed.

 

Even if you doubled the wall thickness of a titanium headpipe, it would still be more brittle than a SS headpipe.

When thicker, it will take more force before being damaged, but it will not deform, it will crack.

 

When you keep saying 'stronger' you are just using an adjective that is intangable in trying to desribe a metals' properties.

 

What you mean to say is that it's AXIAL resistance to deformation is higher than SS.

 

....but that is EXACTLY what you don't want, is a high resistance to deformation, because that MAKES IT BRITTLE!

 

That is why the use of Titanium is limited to linear/axial structures when it is thin, and when it used for radial strength, it is usually very thick (like and artificial leg bone).

Edited by KRANNIE

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Krannie keeps talking about pure titanium, which no one uses. Titanium alloys are used, typically Ti6Al4V. Like ive said before, has vastly different properties than pure Ti. Area under the curve of stress/strain is toughness. It demonstrates the materials ability to do work by absorbing energy. Which gr5 Ti alloy has in abundance over almost all alloys.

It is yourself that does not understand the terminology. Toughness, modulus of elasticity, UTS are the properties that you should be worried about. No one uses anything referred to as coefficient of plasticity.

No such thing as radial strength, there is tensile and shear strength.

And cellular structure in alloys? No such thing buddy. Alloys have crystalline microstructures. I doubt you have even the slightest understanding about these as you dont even know the terminology.

You clearly are lacking in your understanding in the properties of materials so keep your misinformation to yourself and stop preaching it.

If SS were so much better it would be used in motogp, space exploration etc. SS has worse properties than mild steel in all areas except corrosion resistance.

So kran, stop talking shit

Edited by xy500

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ok, just to be a dick now that XY500 isnt apperantly listening to what I said.....

Never once did I say I have any metallurgy degree or use it in a professional matter, i even went out of my way to say I didnt.

Your arguement on pure Ti vs Grade 5 isnt going to help you here either. I (and I doubt you) have no damn clue what class Ti is used in any part, be it the header or Valves.

The arguement being made that titanium headpipes are not weaker, they are just thinner. Come on, this is simple cause and action. Because all the Ti headpipes are thinner, therefor they are weaker and bend / break easier. You kinda just walked back on your own arguement that Ti headpipes are stronger than SS, but you are agreeing that the Ti headpipes have issues because they are thinner.

Seriously, just quit trolling and name calling people, you have brought no useful information to this thread

Not having a go at you at all mate. I do disagree with you saying x head pipes are weaker than y. It all depends. There is no true blanket statement as they all use different thicknesses etc. There is truth to materials though. So as gr5 Ti is higher UTS you can use less material. Its toughness is more than double SS, so just because its thinner doesn't mean it is a weaker part, as stainless is far more prone to stress fractures. A thinner section with the same other dimensions will give a smaller area moment of inertia which can lead to higher chance of buckling but the higher tensile strength more than makes up for it. I'd be far more worried about cracking.

I just can stand for bullshit being purveyed as truth. If you want to compare apples to apples and understand what the best choice is for you it always helps to have a basic understanding of the properties and what effect they have.

Edited by xy500

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