Thanks for the suggestions on the pipes guys. Now let me throw another one at you. I ride in an area that has noise restrictions, which pipe has the least in noise gains compared to the stock exhaust. Do I have to give up performance to have a quieter exhaust? What are spark arresters for and where are they located?

 

The pipes with diffuser disk pipes are the easiest to adjust noise output and performance (more disks=more noise=more top-end;less disks=less noise=morebottom-end). And unfortunately most pipe makers don't/won't list dB levels....it's not the noise that gives you power---remember that......it's design that gives you the power....

Spark Arrestors are small screen that are inside most silencers to keep hot sparks from exiting the pipe and possibly starting a fire. Most all public riding places will require spark arrestors.

Do a Google search for a review of a specific pipe (Supertrapp/White Bros/ProCircuit) and you should end up witha comparison of dB levels.....

 

I dont know if you have a 400 or a 500 but whichever it is the HPd pipes have a lot more of a power gain than any white bros or pro-circuit pipes. HPd has a powermaxx pipe for the 500 (im guessing thats what you have) and while Im not certain of sound levels if you talk to the guys at HPd they will tell, but I am certain you will get more power out of it than an e-series (they lose power!!). So check into HPd www.hpd-inc.com and usually you can get a scilencer and header from HPd for the price of a e-series slip on.

Good luck


Nate

 

The discs themselves are spark arrestors , the gaps between the discs reduce the possibility of sparks leaving the exhaust enough to pass the federal test . This type of arrestor was originally patented by the disco-jet corporation . I suspect the patent is now *expired* because so many companies have copied it . Fair is fair I guess , it was stolen from the steam engine folks who used the design as a steam diffuser long before any of us were even a gleem in our daddys' eyes .

As a general rule you will find discs and cap on the end of a glass packed silencer , powroll had a mechanical muffler that they used them on at one time . In my experience , most of the time you will get best performance with the correct sized silencer core and then enough discs to allow the core to flow air on a flow bench the same amount that it would flow if no discs or cap were present . Removing discs will lessen flow ussually amounts in a decrease in performance , adding more discs than needed doesn't help a thing . Deciding the number of discs is the last step taken after correct core diameter is established .

On a 500 scrambler the HpD pipe does seem to be the best one available for the application and it is quieter than most pipes available . The HpD muffler has a lot of volume , it can *absorb* and handle more pulses than a common glass pack . This is hard to explain in text , but it is correct .

On the 325's and 330's I use an E-series style muffler on our headers that has the correct size core and correct number of discs on it . We have good gains , the reason is we have done our homework .

Rick

 

Rick, is there a way to add a spark arrestor to the HPD Powermaxx exhaust? Or at least put a screen or something in there to make it look like it has one?

 

I am sure one could *fake out * the rangers with use of a number stamp set , but , I would never advise that .


The screen type arrestors (skyway patent) are the worst performing arrestors available , if I wanted a spark arrested Hpd power maxx muffler , I would test flow a pice of tube the same ID of the exit tube on the HpD muffler , then test flow some 2.5" supertrapp discs and get a *match * for the tube (12 would probably do it - just a guess) . Then I would mount those to the exit tube . This would look like something of off Lost in Space , but it would work well and be LEGAL in the forest . The super trapp cap has the legal mumbo jumbo on it that would please the rangers .

Rick

 

Well, I already "stamped" the muffler with the same stampings that were on the factory can. Plus, I make sure it is ALWAYS muddy on the trail. The good thing is that the rangers can't stick a stick up the end of the muffler cuz of the turndown that it has. But, I have heard that the rangers at Silver Lake have a flexable pole. Can that idea with the Supertrapp discs work with the turndown?

 

I'd think with a turndown and disks you'd kill your exhaust---not enough outlet openings....On a Supertrapp IDS2 the gaps between each disk is like 1/16" (or something small like that) and then a large opening at the end of the silencer, so with a turn down like the stock pipe wouldn't allow for enough exhaust to escape.

And it's the closed end cap that makes the Supertrapp a USFS spark arrestor. From the Supertrapp documentation:

All SuperTrapp® exhausts are USFS Approved Spark Arrestors and are legal regardless of the number
of discs installed, providing the Closed End Cap is used. The optional Open End Cap is
designed for Closed-Course-Competition only and will void the spark arrestor function. All systems
are supplied with 12 discs (plus one blank disc described above) to provide a range of tuneability.
Additional discs are available in 6 or 12 packs.

Spark Arrestors don't rob that much HP (maybe 1) so why not be safer than sorry?

 

That is correct , it is not a spark arrestor unless it has the cap on it . With an open end the lit pieces of carbon will sail right through .

The HpD pipe has a down turn on it , it performs well . Adding the correct number of discs will make no difference in power output , the muffler won't even know it's there .

The what to do this is put the muffler on the flow bench , start pushing air through it then add discs til it flows as well as it does without any discs on it . I would guess 10 to 12 discs would do it . (The cap needs to be used in this testing too, that is a given )

I am not recommending redesigning HpD's exhaust . It is a fine piece , I am just explaining how one would add a spark arrestor to an exhaust that didn't have one .

Note : When I do stuff like this I use 2.5" supertrapp discs , not the 3 " series . I have an ample supply of them here at my shop from a purchase I made 15 years ago at a distributer closeout .

Rick