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underground-mpyre

Is a full exhaust powerwise even noticeable on the trails?

37 posts in this topic

So I am looking to get a FMF Full Powerbomb Q4 exhaust in a couple weeks for the 426. I know adjusting the carb is necessary too to tune it. But is a full exhaust even noticeable powerise on the trails? Anybody regret shelling out the money for it or think it wasn't noticeable gains to do it?

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Just my opinion here. But I've never thought that the gains from exhaust was ever worth the cost. I know most would disagree, but I think for the money, suspension mods, or brake mods (oversize rotor), or anything that may improve handling is a better place to put your money. May not look as cool as exhaust, but to me they are usually more noticeable as a rider.  426cc is a lot of power. If you need more just twist the grip. Again just my honest OPINION.

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That is what I am thinking too. I can get my bike to wheelie and that is good enough for me, but was thinking of the Q4 FMF exhaust with maybe a Powerbomb pipe. Right now the ONLY thing I want to do is some trail riding and getting lost in the woods. If I do that, there is plenty of power to climb and haul ass, would I really need a full exhaust or even it being noticeable?

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For a WR a muffler is actually a big improvement over stock. However, you can modify the stock exhaust for free and get results close to a performance muffler.

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Tell me more!

 

 

I am not 100% sure how the exhaust is set up on the 426, but on the 450 for the last decade or so you can unbolt the end cap on the muffler. Under this cap there were 4 allen bolts that hold in a recuder and the spark arrestor. Remove these bolts and discard the reducer (save the spark arrestor to reinstall). Now, if this isn't enough for you, remove the muffler from the bike, take a long 1/2" drill bit (or similar large size) and you can drill 3-5 holes through the internal baffle walls to make the muffler more of a straight through style. I suggest doing the drilling in steps because once you drill the holes you can't go back and the more you drill the louder the bike will get. First you should just remove the reducer then ride it and see if it's enough of a difference. If not, drill one 1/2" hole, put back together and ride it. Keep adding holes and riding until you find the balance between power and noise.

 

In my 2006 WR450 I removed the reducer and put 3 holes through the baffles, but I wish I would have stopped at 2 because it was a bit louder than I would have liked.

 

Like I said, the 426 muffler may be slightly different, but I would bet that it's similar and these mods will still work.

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It has nothing to do with 'power gains'

It's about power delivery quality:

 

- less hesitation

- more control

- wider power band

- less shifting

- quicker reving

- ...and a little boost to the power

 

It is WAY more important to have quality power delivery on trails that it is on a track. Track is wide open, groomed, and predictable terrain.

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Getting the suspension setup for your weight and riding style is the first mod you should do IMO.  It ain't sexy though :ride:

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I had an 01 wr250f for a few years.  When I got it, it had the stock pipe which is the same muffler as your bike.  It was loud with the GYTR tip in it.  I got an FMF Q4 and megabomb which was quieter than the stock, any power gains had to be small enough that one would need a dyno to tell. 

Once you go that route you will need to repack often.  Q4s have a perf pipe core with a perf sheet screen in the middle.  Metal mesh around where the screen is and fiber around the whole core. The newer ones have a bulge and are slightly quieter but basically the same. That screen comes loose.  2 bikes with this pipe and both did it.  I put hose clamps around it and it helped.  The pipe sounds reasonable when new but after only a few hours it was noticeably louder.  I had to fix the mesh and then repack after a few rides.  

I got sick of it and put a mechanical baffle inside of the Q4.  I have a 450 which I am going to do the same thing.  If the pipe manufacturers would build a low restriction mechanical baffle pipe that was just a little louder than stock and never needed a repack I would think they would have a good market for it.  

My 2 cents about pipes. 

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After putting a full exhaust (gytr/pro circuit header) i did notice gains in power but the bike overall felt alot more snappy and the power delivery was there when needed. Very soon after i setup my suspension with racetech goldvalves and springs front and rear and a new set of tires. After all this it became a different feeling bike all together! Setting up the suspension can be a bit pricey though.

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I did a Q4 slip on for my 12 WR450. Would do it again in a heartbeat. Bike is way more responsive.

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Sorry, got caught up in the suspension mod vs exhaust mod and didn't answer your specific question.  IMO, changing out the restricted muffler is a mod that should be done.  For the money, i would just go with a slip-on muffler.  I originally went with the FMF Powercore but after it was eventually damaged i went with the Yoshimura RS2.  I liked the sound output better on the Yosh and the build (welds) look to be better.  Don't know that I can really tell the difference in performance between the two.  But just putting on a new muffler, re-jetting, and opening up the air-box will help the bike breath better and run cooler and perform better.

 

That being said, it can perform at it's best but you will still be deflecting off of every rock or wallowing in every whoop out there if you don't get your suspension setup for you so you will not realize the performance gains you just paid for.  Your bike will run better and cooler, you will just get beat up quicker and thrown around sooner :goofy:  ;)

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The more I did to let the power free from this poor WR engine the more I liked my bike. With every small motor mod the bike felt like it became lighter as it responded quicker and felt like the race machine it was designed to be. I absolutely hated the bike and was going to sell it until I installed a YZ silencer. I couldn't believe the difference. If you are going to be carrying all the heavy metal of a 450 around you may as well make power to make riding a big 450 worth it

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Thanks for your replies. Is my exhaust on my 426 stock, looks stock though, it says "Titanium" on the rear end cap?

Have you posted a picture of it? That would help but base don't he wording "titanium" I would say at least your end cap is not stock. Yamaha didn't put anything with titanium on there exhausts.

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All the early WR headers are titanium

Alll the early 400/426 YZ exhausts have a titanium body.

Is the OP's bike a WR or YZ? Guess I missed that as this is in the WR forum.

The early (2002) WR headers and exhausts were stainless. Where did you get the info they were titanium?

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It say above the exhaust pipe hole on the end cap "Titanium". Sorry I am at work and don't have a picture of it. But added the side picture of it. Looks stock except the end cap.

WR426.jpg

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