It IS possible to shorten the stock exhaust, while keeping the same sound.

[gilmorec61]

Hey guys, this ones mainly for @CZroe, but im sure there may be others who may be interested in this. Last weekend i opened up my stock exhaust and gutted her out, and made my own 'aftermarket' exhaust. I love it!

However, @CZroe asked if there was a way to shorten it(because it looks better) but keep the same sound. I 'think' it may be possible. Im at school right now, so no pictures, but later when i get home, i will post pictures.

Anyways to do this, the catylitic converter in the very beginning of the can WILL have to be removed. However, this shouldnt effect sound. If it does, not by very much because all it is is a 6 inch perforated tube like thing. So pull that out, the cut off the desired length of the can, then cut off that length off the internals of the can.

Then weld it back together and you have a better looking, stock sounding can.

IMO i like it loud, but i know theres a few of you that like it as it is.

Will post pictures later!

[CZroe]

Awesome to know! I don't have the stuff to do it anyway, welding OR cutting, but I still hope to do it some day. It's why I've been holding off on painting my exhaust. Did you do yours at a school welding workshop?

[gilmorec61]

Awesome to know! I don't have the stuff to do it anyway, welding OR cutting, but I still hope to do it some day. It's why I've been holding off on painting my exhaust. Did you do yours at a school welding workshop?

I could DEFINENTLY help you cut it and what not. I did everything at my place, then the welding i went to Taylors dads house b/c he has a welder and did it there. However, i was planning on taking it to CEC and doing it, so if we do yours, we can either take it here(to CEC) or i can talk to his dad and see if he might be able to do it.

Just let me know!

[CZroe]

Originally Posted by gilmorec61

*snip*

That would be awesome. CEC didn't have a workshop when I had college classes there. Are you sure they're OK with you bringing in outside projects? If not, I'd be glad to give Taylor or his dad a little something for the trouble (you too, of course).

The main reason I want to keep it quiet is because I've always been hard-of-hearing and it has gotten notably worse commuting on the bike every day, so I need to keep the noise level down as much as possible to preserve what hearing I have left. That said, the undertail and hugger are mostly blocked by the exhaust when it's parked and leaned over, so I want to minimize the size and tone down the color. A little louder is fine because the wind at speed has always been much louder and that's the level I need to stay under.

Has Taylor made any mods to his 'zuki GSF500 yet?

[choneofakind]

earplugs

[CZroe]

Originally Posted by choneofakind

earplugs

Then let me elaborate: I began using earplugs when I noticed the hearing loss but I avoided it prior to that so that I could use my Bluetooth kit. Now that I no longer commute on the freeway every day and I have a much quieter helmet, I'd like to begin using the Bluetooth kit again. Significantly increased exhaust noise would be counter-intuitive.

[Mulholland]

Everything you described sounds lik it will directly make the exhaust louder... shortening the effective length of the silencer as well as removing the internal cat.... why wouldn't it be louder and less refined?

[choneofakind]

It would still be significantly quieter than a slip-on because the chambers would still be in-tact, and the exhaust gasses would still have to flow in an S-shape through the pipe. Volume change would have no effect, because that only has an effect when you're considering the volume of the fiberglass packing material in a slip-on. My concern would be an actual decrease in flow because the S flow would have tighter turns and would require more pressure. You might lose a little top end, but you can always re-jet later and go to a smaller main jet at the same time.

While it wouldn't be as quiet as the full stock muffler, it would be much quieter than a slip-on, which is just a glasspack.

[Mulholland]

Originally Posted by choneofakind

It would still be significantly quieter than a slip-on because the chambers would still be in-tact, and the exhaust gasses would still have to flow in an S-shape through the pipe. Volume change would have no effect, because that only has an effect when you're considering the volume of the fiberglass packing material in a slip-on. My concern would be an actual decrease in flow because the S flow would have tighter turns and would require more pressure. You might lose a little top end, but you can always re-jet later and go to a smaller main jet at the same time.

While it wouldn't be as quiet as the full stock muffler, it would be much quieter than a slip-on, which is just a glasspack.

The vollume change is half of what the S shape is doing to quiet exhaustunless I am mistaken.... how does shortening the can decrease the radius of the bends within the same circumference can? I need to see a good picture of this badboy cut open if we're going to keep theory crafting lol.

[choneofakind]

The radius of the turns would be the same, but the gas would be being pushed through the S in less distance. The turns themselves would be closer together. Now that I think about it, I'm not sure that would really harm the performance characteristics of the can at full throttle or not.

The reason I don't think it would make a difference in volume is because there's no packing in there. The sound is physically blocked by the fact that the exhaust gasses have to turn so drastically and there's multiple chambers for sound to get "trapped" in. Removing the CAT in the front of the can shouldn't have a huge effect either on dB level because it's just a perforated tube.

There's pictures on the $36 muffler thread. Search time.

[choneofakind]

http://www.2fiddy.com/2008/07/shortie-exhaust-homemade/

[gilmorec61]

Okay guys, im gonna post a few pictures and explain things the best i can, and along with that one link, you guys should be able to figure it out.

Okay, this is everything that came out, got cut off when i made my glass pack:

DSCN0275.jpg


Keep in mind that what we are trying to do is shorten the stock exhaust, but keep the baffles. This is what it looks like lengthwise:

DSCN0269.jpg

This is what it looks like from the ass-end(where the exhaust comes out):

DSCN0271.jpg

DSCN0272.jpg

Keep in mind that there was a cap welded onto the tube that looks somewhat shiny. In this mod you wouldnt have to cut it off because you are still keeping the stock baffles.

This is what it looks like from the front end(where the headers connect to the exhaust) :

DSCN0270.jpg

There is about 6-8 inches of round tube in the front of the baffles. That
should be able to be cut off.

But to make clearance for everything once you cut it off, you MUST remove the cat. converter which is a PITA to get out. And im not sure if removing that by itself would effect sound much as all it is is this :

DSCN0273.jpg

After you remove that, you would cut the baffle to the length you would want it(the red line) :

copy.jpg

Then you would cut the shiny part, the shell of the baffles/exhaust to length. It wouldnt have to be EXACT.

Then you should turn out with something like this :

DSCN0276.jpg


The angles and turns of the exhaust flow "S" would be the exact same, however, it would reach the first tube as soon as it came out of the header, vs. going about 6-8in before hitting the first tube.

Im sure im missing a few things that i will incorporate later, but i hope this clarifys some things.

[choneofakind]

...so basically, it would be the same performance and everything. Same dB level, same jetting, same pressure. interesting!

[gilmorec61]

That would be awesome. CEC didn't have a workshop when I had college classes there. Are you sure they're OK with you bringing in outside projects? If not, I'd be glad to give Taylor or his dad a little something for the trouble (you too, of course).

The main reason I want to keep it quiet is because I've always been hard-of-hearing and it has gotten notably worse commuting on the bike every day, so I need to keep the noise level down as much as possible to preserve what hearing I have left. That said, the undertail and hugger are mostly blocked by the exhaust when it's parked and leaned over, so I want to minimize the size and tone down the color. A little louder is fine because the wind at speed has always been much louder and that's the level I need to stay under.

Has Taylor made any mods to his 'zuki GSF500 yet?

Oh, you went there? Thats sweet! And ill give my teacher another talk, but im almost positive its okay, ill make sure tomorrow. And if he says no, ill talk to Taylors dad. And nahhh, you dont need to give me anything, you should already know i love doing this kind of stuff, so its cool

You know, you really need to come check out my bike before you go through with it, maybe take it on a few mile ride just to see the difference in sound. You may find that what i did isnt too loud, and we may be able to make one of mine for yours! Either way, its your choice

And only one, he chopped his rear fender off. I think hes actually going to sell it soon to get a car. He says he misses his stereo and everything, i dont blame him! But i think id still keep the bike :P

But yeah, just hit me up sometime and we can work on that can!

...so basically, it would be the same performance and everything. Same dB level, same jetting, same pressure. interesting!

Well those are the intentions!

[gilmorec61]

@CZroe , i just talked to my welding teacher, and he said that it would be OK to bring her in and weld her up

[str8t six]

do you have a video of it?

[CZroe]

Originally Posted by gilmorec61

@CZroe , i just talked to my welding teacher, and he said that it would be OK to bring her in and weld her up

Thanks a ton, Chris! Let me know how it goes. I came home after cutting it with you last night and blew my nose to find all that rust in my nose! That's what I get for letting it get so rusty.

I got my account sorted so I'll get some replacement cutting wheels and stuff if you tell me what type/model. Thanks again!

It sounded like you wanted me to see how good your welds were under the cap, but I have no idea what a bad weld looks like anyway and I know you do good work. Awesome.

[CZroe]

Got it. It looks great! I can't wait to install and hear it. I'll let everyone know what it sounds like ASAP. :P Thanks again, Chris! LMK what the model/part number is I can replenish your cutting blade supply and I'll get it right to you!

[choneofakind]

Video needed Jet

[CZroe]

Originally Posted by choneofakind

Video needed Jet

I don't have anything recorded to compare it to, but here:

Link to original page on YouTube.

[choneofakind]

That sounds pretty darn good!! A little deeper, and I honestly wouldn't even notice that wasn't stock if I didn't know. How's the jetting feel? any different than stock?

[CZroe]

Originally Posted by choneofakind

That sounds pretty darn good!! A little deeper, and I honestly wouldn't even notice that wasn't stock if I didn't know. How's the jetting feel? any different than stock?

Yep. Definitely sounds deeper. I haven't ridden on it yet but half the reason of trying to maintain the same back-pressure was to keep all that the same so I wouldn't have to pay someone to tune the jetting and stuff I know nothing about.

The reason for doing anything at all was cosmetic, to reveal more of the Sportisi undertail and hugger. The hugger's on the ground and it's too dark to see the undertail in the video, but I'll show all that off when I paint the pipe, clean everything up, and throw it all back together.

[gilmorec61]

Ill try and get a video of my exhaust then youll have something to compare it to Im at school right now so i cant view the video, but i will as soon as i get home !