SuzukiSavage.com /cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Supertrapp Muffler for Savage /cgi-bin/YaBB.pl?num=1717939840 Message started by ThumperPaul on 06/09/24 at 06:30:36

Title: Supertrapp Muffler for Savage Post by ThumperPaul on 06/09/24 at 06:30:36 Got a tunable "Supertrapp" muffler designed specifically for the Savage off a parts bike I bought.  It even has the 10 degree bend at the inlet so it lines up with the header and mounts up to the stock mounting bracket clean and square.   DBM - You need this Supertrapp muffler to add to the 7 mufflers you've already tested in your muffler shootout!  You'd have fun!  You'd have to test this one 6-7 times with your vacuum contraption!!  You can add/remove discs at the outlet to tune the muffler.  More discs, more open, more flow = louder.  Fewer disc, more restriction = quiter. It currently has 5 discs installed.  Supertrapp's basic instructions suggest 6-8 discs for a stock Savage or else you have to rejet the carb richer if you install more than 8 discs.  I think you can stack up to 12 discs, and then there is also an option for a closed or open end cap.  This one has a closed end cap (default setup).  These things are like $700 brand new!  Whoa! https://supertrapp.com/catalog/product/view/id/11326/s/supertrapp-728-50650-megaphone-series-slip-ons-suzuki-ls650-svg-86-04-s40-05-16-chrome/category/2/ Anybody played with one of these?

Title: Re: Parts Bike or Big Project ?! Post by Surviving Philly on 06/09/24 at 08:31:11 Paul what would you be willing to to part with the muffler for??? Ive been dying to get my hands on one of those but would never justify the price of one new.

Title: Re: Parts Bike or Big Project ?! Post by ThumperPaul on 06/09/24 at 09:56:52 Well dang it, Philly!  Why do you want the 1 part I’m most curious about too!? I’m going to remove it today and see if I can get the end cap and discs removed.  I’m hoping the screws aren’t seized up.  I’m letting some PB Blaster do some work right now. Side Note - I decided to blow off the fork brace for now, otherwise I might have offered you a trade. Let me look at this thing.  I’ll share some photos in a separate post for you and the forum.  Agree, I’d never pay $700 new when a gently used Dyna muffler can be had for $50 or less.  But it’s clever how this thing is designed for the Savage and the muffler inlet aligns properly with the header pipe.

Title: Re: Parts Bike or Big Project ?! Post by Dave on 06/09/24 at 16:03:22 When I bought my 2007 that is now my Cafe' bike - it had a Supertrapp on it. If you like your motorcycle a bit noisy - you would probably like it.  I bought an extra pack of discs and fussed around with it a bit. It was just too noisy for me and I got rid of it.

Title: Re: Parts Bike or Big Project ?! Post by ThumperPaul on 06/09/24 at 16:22:44 Dave - I think you've tried about everything! I read an old post about it and seems people are/were using anywhere from 7 to 14 discs.  Do you recall how many discs was too loud for you?  The Supertrapp instuctions suggest 6-8 discs for the Savage.  This one only has 5 installed.  I can't see how the thing breathed with only 5. Honestly I can't see how the thing works with any number of discs - the gaps between discs are tiny. I'm having trouble removing 2 of the 6 screws.  Justin O said he had the problem too back in the day.

Title: Re: Parts Bike or Big Project ?! Post by verslagen1 on 06/09/24 at 16:32:43 not an unusual problem with the trap. like all screws associated with exhaust, they tend to corrode and weld in place. but you can remove the entire core by removing the 2 bolts located on the outside of the can, near the bottom. remove those and the whole thing will slide out.

Title: Re: Parts Bike or Big Project ?! Post by Michael Moore on 06/09/24 at 19:44:51 FWIW, on my 750 Laverda we got to around 20 discs on the end of the megaphone before there was no difference between the open exhaust and the ST discs in power on the dyno.  However, the noise level was much more tolerable. http://https://motoconstructor.com/graphics/Laverda/LavSF2RRMK5012a1.jpg SuperTrapp used to make reverse-flow inserts with discs for the Kerker/Bassani/etc 4-1 exhausts back in the day.  My engine tuner made copies of those.  They did not have any fiberglass/ceramic wool packing, just the reverse flow tubes and discs on the end. WIth the ST discs you can get an improvement in flow by stacking up the discs on the lathe and using a sharp boring bar to take out the small reverse lip on the interior that seems to be there for spark-arrestor purposes.  The discs have weight, so reducing the restriction so you can then drop the number of discs does help.

Title: Re: Parts Bike or Big Project ?! Post by ThumperPaul on 06/10/24 at 05:54:41 Thanks Verslagen.  I saw the core screw (one of my ah-ha moments!).  Those are stuck like chuck!  Those Allen heads are probably going to strip out, and I’ll probably end up slotting them or try vise grips if I can get a bite on them. Micheal - the discs seems to stack in manner that won’t allow exhaust gases to escape.  It’s weird to me..  It’s like they are stacked directly on top of each other in the center and the screws are on the outside of the discs/cap.  How do the gases get out?  Apparently they squeeze out, but it seems restricted even if you put 30 discs on there! Instead of more discs, what if you used washers (spacers) to widen the gap between each layer of discs to create a wider gap?  Would this work to increase flow?  Bad idea?  Six washers are cheap compared to a disc.  I think you get where I’m going with this - instead of more discs, what if the gap between each disc is widened to allow more flow.  Like 5 discs with washers between discs would equal something like 10 discs (something like that).  Need DBM to hook it up to his vacuum cleaner contraption! Side note: I’m guessing the thing buzzes like crazy if the screws get the least bit loose.

Title: Re: Parts Bike or Big Project ?! Post by Michael Moore on 06/10/24 at 08:55:39 Paul, all the ST discs I've seen have been made to be used in their spark arrestors, and that small lip I mentioned makes the flow reverse to go between the discs and the space is very small between discs.  My presumption is the hot particles/sparks keep going past the gap to be trapped inside the ST or get lodged in the gap and lose their heat into the disc.  If you zoom in on this you can see the very small lip on the ID: https://m.media-amazon.com/images/I/61Xj1jXaqXL._AC_SL1088_.jpg Since the spark arrestor function wasn't needed on the race or street bikes using a very sharp tool bit in the lathe to turn off that reverse lip made the fit between the discs less restrictive so the same amount of flow could be had with fewer discs.  The discs are stainless steel and if the tool starts to rub instead of cut they'll work-harden. Here is the patent document for the discs that has some detail drawings and text explaining how they work https://patentimages.storage.googleapis.com/05/9f/8b/ee4282ad4cfa3d/US6467569.pdf I think you'd need to be careful about spacing the discs apart or you'll loose the circuitous path the gases must follow to exit the exhaust.  I'd expect that the straighter the path, the less energy (noise) the exhaust will lose. Part of the noise attenuation is also due to the 360* exit.  If you stand directly behind a straight through muffler you get all the noise.  If you stand to the side you experience less of it.  So the ST discs will cause much of the exhaust to be directed away from the listener.  It is the same idea you'll see used on race vehicles where the sound meter is always in the same spot at the side of the track -- put a bit of a tip on the end of the exhaust to direct the noise to the side away from the meter.  The exhaust isn't really quieter, but it foxes the measurement.

Title: Re: Parts Bike or Big Project ?! Post by ThumperPaul on 06/10/24 at 11:17:39 Cool how you found the patent!  That’s some good info!  So washers = bad idea = I’m no engineer! This thing must be pretty toned down with only 5 discs.  Especially when Supertrapp recommends 6-8  discs with stock jetting.  I’ll probably open the carb later today to see how it’s jetted with the 5-disc muffler tune. Curious how many discs Dave was using when it was too loud for him.

Title: Re: Parts Bike or Big Project ?! Post by Michael Moore on 06/10/24 at 15:54:07 Google Patents and the Euro patent office espace can turn up some very interesting information. Keep in mind that the number of discs needed will vary with the diameter/circumference.  If you are using 3" discs you'll need a lot more of them to have similar restriction to a few 4/5/6" discs. https://motoconstructor.com/graphics/exhaust/ If you look there I've got photos of the ST baffle insert that my friend copied, including a dimensioned photo and also the box labels in case someone wants a project to build their own: http://https://motoconstructor.com/graphics/exhaust/STbaffle02length.jpg http://https://motoconstructor.com/graphics/exhaust/STbaffle02OD.jpg http://https://motoconstructor.com/graphics/exhaust/STmufflerinsertsmboxall.jpg

Title: Re: Parts Bike or Big Project ?! Post by verslagen1 on 06/11/24 at 12:10:56 interesting design, I believe the 2 forward tubes direct the pressure waves to the back wall which reflect towards the front and tend to cancel each other out.  This repeats with the forward wall before exit. Do you have any recordings? The back cap appears to be open so I don't know what impact the discs will have on sound level.

Title: Re: Parts Bike or Big Project ?! Post by Michael Moore on 06/11/24 at 12:23:46 The cap is the standard 4" ST steel truncated cone with a center hole for the retaining stud, so any exhaust has to leave via the discs. No recordings of the sound are available as this was all back in the 1980s/90s.  My friend Steve (the CBR600/XS650 special) had one of the copies of the ST insert in that exhaust.  But that was 20 years ago too, and I can't recall how loud it was, though I'm pretty sure it definitely was not quiet.  But then he was not trying to make a very quiet street bike so he didn't experiment to see how quiet he could make it.

Title: Re: Parts Bike or Big Project ?! Post by DragBikeMike on 06/11/24 at 18:01:04 Well at least they made an effort to attenuate some noise.  I suspect the directional change helped a bit, but they eliminated the packing, so you lose the absorption.  I bet it lets a lot of high frequency noise through. There's been some talk about the discs not having any gap.  Those dimples around the circumference of each disc ensure that they don't stack up solid.  The dimples set the gap between each set of discs. I personally am not a fan of SuperTraps.  They are loud and they emit a lot of high frequency racket, but I must admit they flow real good when you pile in the discs.  I've run them in the past and they made good power, but once I flunked safety check and had to drag my butt home and swap mufflers.  Not only are they loud, they are irritating.   Based on those beautiful pics, I would be tempted to try and incorporate a good baffle along with packing.  The basic shell is valuable.  It's decent size and has the right jog at the inlet so it bolts right up to the Savage.  An industrious individual could fabricate a nice reverse cone that would allow more volume to house the baffle.   With a little clever engineering you could set it up with a thin layer of wool packing that hugs the shell, then maybe use a 1" or 1.25" baffle tube with a center plug and ample perforations.  You would have a nice mix of moderate restriction, directional change, and absorption.  You might have to do frequent re-packs but I expect it would be easy.  I believe Dave did something like that to a reverse cone muffler he runs on his cafe except it didn't utilize wool packing. Thanks for the pics.  Very interesting.  I've never seen that particular SuperTrap baffle setup.

Title: Re: Parts Bike or Big Project ?! Post by Dave on 06/12/24 at 03:52:00 If I had known what I know now.....I might have been able to take the db of the Supertrapp down a bit.  That insert for the Supertrapp looks creative! The muffler I built for my Cafe' bike has been pretty good.  It is a bit restrictive I believe - but the sound has been reasonable and it is a compact muffler. It uses and Emgo chrome housing.  The first setup is what is shown in the photo posted here.  The first baffle is removable and it has a plug in the center - the exhaust enters the inside of the perforated pipe and then is forced to the outside into the area between the baffle and the muffler shell, then it has to enter back into the perforated pipe before it enters the rear baffle.  The rear baffle does the same - the exhaust enter the inside of the pile and then a plug in the center of the pipe forces the exhaust into the outside shell, and then it goes back into the perforated pipe before it exits. This pipe worked OK and does a pretty good job of cutting the noise down.  The really hot exhaust gasses exiting the first baffle does make the outer shell really hot and the chrome has turned blue/black in a small area at the bottom where the chrome does not get a lot of airflow on the outside of the muffler.  I do believe the muffler was a bit restrictive at full throttle and high rpm - but that is OK as I don't go there  often.

Title: Re: Parts Bike or Big Project ?! Post by Dave on 06/12/24 at 03:58:16 The next thing I tried was to take the first baffle and remove the interior plug to allow the gasses to flow straight through - then wrap it with stainless steel shavings that came from cutting down a brake disc OD.  I used stainless packing as this area gets really hot and glass wool would burn out instantly. This didn't seem to work any better at cutting down the noise....and it actually got a bit louder.  It likely did cut down the heat on the muffler shell a bit - but the blue/black discoloration at that spot is permanent and can't be buffed out anymore.

Title: Re: Parts Bike or Big Project ?! Post by Dave on 06/12/24 at 04:09:20 I don't have a photo of the current (and final) iteration of the baffle system - but it works like this: The first baffle was returned to being a perforated pipe with the plug in the center - I did drill the holes to make them larger.  The second baffle got the plug removed and is now wrapped with glass muffler packing.  When I tried this it was just a bit too loud - so I welded a perforated metal screen over the back of the muffler to help keep some of the sound in where the glass packing could work on it a bit more. This setup is a little bit louder than I would like - but it is acceptable and works fine for the way I ride.

Title: Re: Parts Bike or Big Project ?! Post by ThumperPaul on 06/12/24 at 05:50:38 Great info and discussion guys! I do like the Shell and inlet angle designed for the Savage.  Just not sure I’m up to the job of modifying it. Mike - you must have really hated this thing since you omitted it from your muffler shootout.  Or too many iterations/scenarios needed to give an evaluation! Texas motorcycle safety inspection:  beep beep, blink blink, can I still see George Washington’s wig on a quarter…. Here - have a sticker.  That’ll be $7.  Actually don’t get the sticker until you renew the registration after passing the safety inspection.

Title: Re: Parts Bike or Big Project ?! Post by Ruttly on 06/12/24 at 10:02:25 My muffler was longer , when it got chopped I made a repackable core. Repack every other year.  Packing keeps exhaust note down , removes hollow sound of an empty metal can. Straight thru at a reduced diameter from header with 2 optional crumb cups that further breakup the note. Flows great , has a quiet growl with an annoying decel crackle , needs a repack. Great match with the VM38 , all throttle , big fun !

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