I had posted instructions on how to do this ages ago but somehow the post has disappeared. I must have referenced it in another post, and I've been contacted by several people asking where the instructions are. Here they are again, for the three or four people out there who haven't yet yanked their stock exhaust & replaced with a set of Arrows or something(that would have been my first choice). This mod makes the stock mufflers sound identical to a set of Termignoni cans, makes them look a lot better, allows for repacking, and costs very little in comparison to a proper set of full Arrows which were #1 on my list. It's a very satisfying mod; so satisfying it made me forget I wanted the Arrows altogether. Sounds and looks best when used in conjunction with an aftermarket midpipe, but that's not absolutely necessary.
Always wear gloves and eye protection when doing this type of work.Materials list two 12" lengths of 2" diameter perforated stainless steel tubing (I bought mine from LA Choppers)
six 12"x10" sheets of fiberglass exhaust packing (again from LA Choppers, sold in packages of two)
stainless steel wool (I have no idea where to get this but it has to be available
somewhere)
bailing wire, stainless preferably (Harbor Freight)
tube of hi-temp copper RTV sealant (any auto parts store)
5/32" drill bit (any hardware store)
5/32" aluminum pop rivets (any hardware store)
one package of metal-reinforced epoxy putty (any hardware store)
one can of Rust-Oleum hi-temp gray primer (any auto parts store)
one can of Rust-Oleum hi-temp flat black spray paint (I used the BBQ Grill paint)
one stick of red polishing rouge compound (optional, got mine at Lowe's)
two packs of
heavy-duty non-reinforced cutoff wheels and one package of
reinforced cutoff wheels for Dremel tool
(very important)
one package of fine sanding discs for Dremel tool
one package of JB Weld
six nuts that correspond to the bolts that attach the bracket to both cans and the heat shield to the top can
some acetone
some medium grit sandpaper
Tools requiredDremel
bench grinder/buffer with a buffer wheel(optional)
various and sundry banging and prying hand tools
bench vise
pop rivet tool
drill (drill press is preferable but not necessary)
long squeeze clamps (handy for one of the steps)
reciprocating saw with ~6" metal cutting blade
The photos are from an S2R800 core job, but I've done S2R1k & S4RS mufflers using the same method. First measure the diameter of the muffler inlets. I think it should be 43mm for the S2Rs and 50 for the S4R/RS. I got 1-3/4" diameter perforated stainless tubing for this project, which more or less corresponds to 43mm. In hindsight, I probably could have used 50mm(2") for the S2Rs as well, as the bigger diameter would have produced more of an Arrow sound vs a Termi and fitting would have been a bit easier. So, just go with 2" diameter. I used three 12"x10" fiberglass exhaust packing sheets per muffler.
PrologueFirst, a general diagram of where you will be cutting the mufflers. Forgive the cartoon, but you get the idea. This was my first attempt. As you can see, I jogged the cuts around the wellnuts in the steel inner muffler casing to preserve the mounting points. Well, with the last set of cans I just cut the inner muffler casings about 1" from the outer inlet housings as pictured. Much quicker and easier with less cutting involved, and you won't have the trouble with the fiberglass packing snagging on the wellnuts when you're trying to fit it all together. This is what the six metric nuts and the JB Weld are for. Also, with this method you will end up with lighter mufflers than with the original method.
To begin, remove the muffler tips using any of the partial-core instructions found elsewhere. Basically you just get a Dremel with a flexible shaft attachment and a heavy-duty non-reinforced cutoff wheel and insert it into the end of the muffler and cut around the inside of the smaller inner baffle tube until it comes out. You will then see two steel straps welded to the muffler tips holding them to the inner steel muffler casing. Use the Dremel to carefully cut them away and free the muffler tips from the mufflers. Don't cut into the tips themselves, just cut through the straps and free them for the time being, and after they are free clean them up further.
Now you can slide the outer aluminum muffler sleeves off both mufflers. Set them aside, and use your Dremel to cut around the inner steel muffler casings as pictured above. Best to use the larger reinforced cutoff wheels for this task. Try to cut as neatly as possible, mark the cut line with a Sharpie beforehand. After you make these cuts you will still need to cut through the inner baffle tubing to lop the whole thing off, so wrap the muffler in a towel or something and carefully secure it in a bench vise taking care not to crush it. Then take your reciprocating saw and finish cutting through the muffler. You should be left with an inlet housing with about an inch or so of inlet baffle tube left.
At this point, you should do the optional polishing step. This involves polishing both the muffler inlet housings and the muffler tips to a high shine using the polishing stick and buffing wheel on your bench grinder. Wear a pair of gloves and goggles and go at it. Polish them up nice and shiny. This will have a stunning effect as the finished photos will reveal. Some people will elect to forego this step as it is not totally necessary, but I think it makes a huge contribution to the looks.
Polished vs. unpolished shown below:
Now on to preparing the outer aluminum muffler sleeves. Get some sandpaper and roughen the inside of the sleeves where the holes for the wellnuts are, then degrease using some acetone. What you are going to do is lightly roughen the metric nuts you bought with a grinder and JB Weld them in place at the holes inside, as pictured. This ensures you have a place to mount the bracket at heat shield, as you cut the wellnuts for them off completely in an earlier step. To ensure precise placement of these surrogate nuts, go ahead and clamp them in while they cure using the stock bolts. Once cured, they ain't going
nowhere so be careful and neat with this step.
Bear in mind - you may chop the sleeves down, but I elected not to as I think the mufflers are just about the right length as is, and also your heat shield will not fit quite right anymore, requiring you to engineer a solution for that. This could be an opportunity to be creative for some of you.
Now on to the innards. Wrap each perforated tube with a layer of stainless steel wool if you can find it, followed by three sheets of fiberglass exhaust packing, followed by a little bit of bailing wire to tie it and keep it wrapped while you are struggling to fit everything together. What the SS wool does is keep the fiberglass packing from deteriorating as rapidly, allowing longer life between repacks. I did not do this as I couldn't find any SS wool anywhere, and also it's not a difficult thing to repack these anyway. Don't use regular steel wool as it will rust. Shove this assembly into the sleeve as pictured. You won't need to flare the ends of the perf tube to fit over the inner muffler tip outlet as in the photo if you use 2" diameter tubing.
Prepare the inlet housing by laying a nice bead of hi-temp copper RTV goop around the flange and carefully slide the sleeve/packing assembly onto it, being careful to not snag the packing and align the perforated tube with the inlet pipe. Filing the edges of the inner steel sleeve after you cut it will reduce the tendency of the packing material to snag and make everything more difficult. Don't worry about the goopy mess that ensues, you will peel it off easily later after it cures anyway. I hate RTV with a passion but it will keep the mufflers from blowing.
Repeat with the RTV on the tip flanges and fit the tips in much the same manner being careful to align the inner perf tubing to fit
over the inner outlet in the muffler tip. Squeeze the whole assembly together with the long squeeze clamps. I used the Irwin Quick Grip kind you can find just about anywhere, with the rubber jaw inserts. Those things are worth their weight on gold by the way, when you need them you
really need them.
Now with the muffler assemblies fitted together, sealed, and clamped, mark the points on the mufflers where you will drill for your 5/32" aluminum rivets. Some people will recommend stainless rivets. That's fine but aluminum will be plenty strong for this and if you ever have to drill the rivets out to repack you will have an easier time. No, the mufflers won't nearly get hot enough to melt aluminum rivets
. Mark your holes. I used one hole centered on each 'side' of the muffler. They aren't round yet not exactly polygonal in cross section either, but you get my meaning. Do this on both the inlet side and the outlet side of the sleeves, for a total of six rivet holes per muffler. You want to drill each hole a consistent distance from the edge of the muffler sleeve to preserve a neat appearance. Don't get sloppy here or it will look like a kludge job. You can do all of this while the RTV is curing, it will be fine. After you do this you may now pop the rivets in each of the holes and secure the mufflers together permanently. Unclamp and let the RTV cure overnight. Take the opportunity to knead a little bit of epoxy putty into a little sliver and stick it in each of the rivet head holes. When sanded flush later, this will help the rivets disappear after they're all painted up.
After curing the RTV and epoxy putty, get an x-acto knife and carefully cut around the mufflers where the goop squeezed out and peel the excess off. This should be self-explanatory - you want all of that peeled off neatly or it will stick out like a turd in a punchbowl due to it's orangey color. Get your Dremel tool and use a fine sanding disc to sand the epoxy putty slivers you put into the rivet heads flush. You will now have small unobtrusive 'buttons' that will go unnoticed when the cans are painted up. That's one of the things that bugged me about muffler core jobs - you could see the rivets easily.
Now you should have a functioning set of fully-cored mufflers, but you still need to paint them. Mask the inlets and tips from the sleeves with masking tape. Get some sandpaper and roughen the aluminum muffler sleeves to better receive the hi-temp grey primer. Wipe off with some acetone and lay a good coat of primer on 'em. Allow to dry and follow by two, three, or four coats of flat black. I should remind you to follow the rules for spray painting here regarding spray distance, motion, coat thickness, etc. After everything is dried and cured peel the tape off and clean any tape residue off the polished inlets and tips with some WD40 and a rag. Congratulations, you're done. Look at these beauts:
And here they are installed:
Video of the result
EpilogueI had the heat shield powdercoated as I was doing some other parts as well. I think it looks good in a darker semigloss finish. Shinier paint would probably be better for the shield as it would stand up against rubbing on clothing better. One could get creative and maybe polish the shield on the buffer wheel, cut holes in a creative pattern then polish it, skeletonize it somehow then polish it, paint it, etc. If anyone does any of this, please post up. I wanna see.
In the end, the sound was
awesome. Just what the doctor ordered. Coupled with flat black ceramic-coated Quat-D midpipe, headers, and s-pipes it made me forget all about the full Arrow set I was saving up for, and freed up cash to spend on other mods. In all I shaved a little over 5 pounds off the mufflers with the original method. Even though I don't own that bike any more, I still feel a sense of satisfaction from this little project. I've done this for other riders and they were all amazed at the quality of finish and tone of these cored stock mufflers. Follow my instructions fastidiously and you will achieve the same. Bon chance and ride safe-
