Stock 426 - what will the different pipes do?

[nikki]

Red (my guy) is considering getting a pipe for his 426. The motor is stock. What kind of effects will the different pipes/silencers have on the power? And what brands are out there (DSP, Dr. D, Yoshimira, White Bros, PC, FMF, etc...?) Will he benefit from an aftermarket silencer alone?

Thanks for any info! :)

 

[biglou]

Nikki-I just bought a 426 last week, but I've been reading about them for a long time trying to learn as much as possible about them. From what I have read, about the best you can do is to move the power around in the rpm range on the YZ426. You might get a peak HP or two higher over some narrow rpm range, but that is about all. For the money, I would send the engine to Eric and Rich. :D

 

[eunos]

Nickki,

Read the thread "AMAs bill dart on thumper pipes" that should provide your answer. Big Lou`s right save the money and invest it, were all going to be buying quieter pipes before much longer.I believe dirt rider mag tested all available pipes for the 426, non made a significant difference over the stock pipe.

Kevin.

 

[motoman393]

Everyone that has a Thunder Alley pipe on www.thumpertalk.com raves about them. They are hand-made by a man in California, and fitted and tested 1 at a time! Here is the website: http://www.taliaferro.net/thunderalley/ Later,

Garrett

 

[Hick]

426 Pipes I've tried

Nikki,

I’ve put many hours on the stock pipe, an FMF Q series, a White Bro.s R series, E series and the Pro Circuit T4. I’ve also recently purchased a Thunder Alley but have yet to try it.

Most systems, unlike the Pro Circuit, will work with the stock header. I haven’t tried all the headers but it seems the main difference in aftermarket exhaust performance over all-stock YZs is the collector and silencer, with most of the pipes I’ve seen being much louder and a little snappier down low but losing a little bit up top. As expensive as a complete system is (header and collector/silencer) many people pass on the aftermarket header. When I ordered my TA pipe I asked the guy who makes them and his opinion was the stock header was hard to beat.

One thing I will say about the Pro Circuit is IMO it is the best engineered and built pipe I’ve seen, but I hear the Dr. D is nicely made as well.

The stock header and collector on the 426 may be the best stock exhaust system made, so your buddy may consider spending his $$ elsewhere. The only reason I ever thought of replacing it was because I need a spark arrestor for the off road events I enter. That doesn’t explain why I don’t just modify the stock can (link: Pro Moto Billet ), so maybe part of it is, like all four stroke riders, I like to have shiny new trinkets to attach to my scoot.
:confused:

 

[J.B.426]

Although I haven't tried any other system, I have done a fair amount of research and I think Hick summed it up pretty good.

If I did buy one, I would either go with the Thunder Alley or Dubach system. Other than those the only reason I would get one would be for the spark arrestor, would probably go with the Pro Moto Billet and not the whole muffler, or go for one that is quieter if I needed too. Overall performance-wise, I think the stock system is pretty hard to beat.

 

[Scott Senatore]

Hick,
I have been looking for a quit muffler for my 426 and have been considering the FMF Q-core. It seems you have tried a bunch of them what is your opinion of the models you have tried.
Thanks

 

[MXN4FUN]

Nikki the only things I've experienced with the pipes I've tried, Pro Circus White Bros and FMF is they are all louderand they melt pants. The exhaust note is more crisp leading to the illusion it is making more horsepower, mhp-mental horsepower. Most on the dyno showed robbing from the midrange to enhance bottom end while only seeing minimal gains on top. The only thing that made a difference was header changes. Not more horsepower but different, stepped or tapered made the hit more pronounced while the oversized seemed more linear. I'm still running an oversized header from FMF built in '98 on my '02 426 with the stock collector.

 

[Hick]

FMF Q

Rick,

I should have mentioned the reason I didn’t keep the Q was because it fell apart. The rear hanger they use is a strap that cradles the can, as opposed to a fixed mount welded to the can ala stock or PC T4.

I think this would be a perfectly acceptable design if:

a) They used springs to hold the can firmly into the collector, resisting movement and vibration, like Yosh does.
b) The can was not so long and heavy. As designed and mounted on a YZF the bulk of the can is actually aft of the rear hanger. This causes the can to put stress on the four small (~ 4 mm) bolts that secure it to the collector since the can will rock to and fro about the axis of the strap-type hanger.

In my case this caused the four little bolts to come lose. I kept an eye on them and had to retighten after every few rides. At any rate perhaps I wasn’t vigilant enough because I guess the bolts ovalled out the holes in the collector to such an extent that it came completely apart during a race, even though I checked it all over the night before and applied loctite and snugged all fasteners. Since the rear hanger isn’t affixed to the can the whole thing just flopped off in a sand wash somewhere in central NM after the four bolts got ripped out of the collector and that was the end of my race day (and the end of my $300 pipe).

I’m thinking they designed it this way (no fixed rear mount) so that one silencer would fit many different bikes, which is good for Mr. Emler but was bad for me. The Q silencer retails at around three honey I think, and IMO it isn’t even close to being worth that. The only other system I know of that is as quiet or perhaps quieter than stock is the Arrow system, which comes w/ or w/out a header, is also very expensive, and last time I checked did not have an S/A. Also, I have yet to see one, much less hear one so I don’t know how quiet they really are.

Oh, I almost forgot, yes, the FMF Q is quiet, not as loud as the stocker and almost as quiet as a stock KTM 520 (at higher RPMs/loads/throttle settings my YZ w/ the Q was only a little louder than my pal’s stock 520 EXC). As for power it seemed to lose a little down low, but revved very well, as good or better than stock and much better than any aftermarket system I’ve tried.

Hope this helps.

 

[Scott Senatore]

Hick,
Thank you for your reply it has helped.