Louder Exhaust

Hey everyone,

I am looking to make my bike louder. (Have you ever heard this before??) :lol:

I love the agressive XJ sound, not a typical V-Twin rumble...sounds more like a muscle car in my opinion.

So I have a question. I do not want to rejet. 8)

If I keep my collector on, and run pipes from there with lollipop baffles, will I need to? Everything else is stock. Not interested in pods or anything, just want to hear my bike a bit more.

 

Im not sure what the internals of the mufflers look like on these bikes. I'd love to see a full section view if anyone has a link to one. I do believe you will have to rejet due to the change in resistance of the exhaust. Its likely that the stock back pressure was used in the calculation of the carb tuning by the design engineers! Any change in intake and exhaust resistance will likely need a proper rejetting. If the resistance is not far off from stock I dont believe you'll need to rejet. Im positive some folks here have experimented with this already. I did see some jetting suggestions in the jet section of the xj4ever store. you might want to give that a look over.

You could try running it with out the mufflers on (I'm assuming you have already), but this doesnt take into account the resistance of the baffles (small) and the change in frequency which effects pressure at the exhaust manifold. untimatly, you want a negative pressure at the manifold when the exhaust valves open. This helps pull the exhaust gasses from the combustion chamber and creates a negative pressure in the chamber to help pull in fresh fuel and air. I would love if one of the gurus around here would chime in with a way to test for this without expensive equipment.

 

The stock mufflers are very similar to most automobile mufflers on the inside. There is no "straight path" through them; usually a pair of "bulkheads" with holes or pipes passing through them that don't line up with the pipes or holes on the other one. Look in the outlet hole of a stock muffler and you'll see a "wall" a few inches inside.

Your bike doesn't have a real "collector box" rather there is a crossover pipe and a set of "Y" pipes. Add to that the complication that the mufflers are welded to the system; you will need to do some minor surgery. KEEP everything "forward" of the original mufflers for best results.

And as much as I hate to say it, Harley Sportster mufflers seem to be very popular for this. There are also a number of aftermarket "slip-ons" available; some light re-engineering required.

 

Even though my bike has chrome cone mufflers it appears they are aftermarket.

They are bolted on, they are about 4 inches longer than my friend's stock mufflers, and the ends have one hole in the center with 6 smaller holes around it vs. just one center hole. Also on mine the baffles are removable with 3 bolts.

I have removed them and rode it for a day. Some things I have noticed:

1. It's loud. But I wouldn't say too loud. Reminds me of a muscle car.
2. Popping on decel more pronounced.
3. Idle is about 800 RPMs higher than it was before the baffles were removed.

Doing plug chops today. It's obvious that there is a lean condition. Going to see if the condition is tune-able. If not, the baffles go back in.

 

The popping could be 2 things. One a lean condition, and 2 the 6 small holes. I had similar mufflers on my 81 650 back in the day It does change the sound, making it a bit more throaty and load. However, I didn't like the sound of the popping and brassed up the six holes. After that, I didn't have any popping issues unless I really rode the bike hard.

 

Alright...after 2 weeks of riding without the baffles I have come to the conclusion that:

It's TOO loud at 5-8K. :lol:

Also it feels like there is less mid-range power.

Baffles are going back in. I still hate the way the megaphone mufflers look, going to look for some Sportster slip-ons.

 

Is that the same with the stock 700 mufflers too fitz? as mine are just straight through

 

Just let your collector rust out. Mines nice n lound

 

Jokes aside, mine came with one it, which I think look pretty badass. I like them a lot more than those dorky trumpets.

It hasn't left the backyard yet, so I can't really tell you how they perform

 

Those look pretty sweet. And truth be told, I love the way the bike sounds at LOWER rpms. But once you get around 5K, it's just too much.

 

I think these are actually downslash sportster mufflers

 

It sounds a lot different to people on the side of the road than it does to you when you ride it. I downloaded a high-quality MP3 recorder on my phone and let it record by the side of the road. Prior to this, I had been a little disappointed in the higher-RPM sound. I was quite pleasantly surprised when I listened to the recording. I'm not sure if I can post an MP3 on here, but if somebody can figure out a way I can put it up.

 

Maybe you can host the file and link to it?

 

Where can I do that? I usually use Photobucket for pictures, but I don't think they host audio.

 

If you have a Gmail account you can upload it to Google Drive and make it public.

 

I'll try that. I won't be able to do it until later, though.

 

Aaaalright, I think I have this figured out. The MP3 file should be at the link below:

https://docs.google.com/open?id=0Bzky4N ... E5UU0tJcDg

At about the 2:00 mark I drive down the driveway and accelerate down the road. At about 3:00 I make a low-RPM pass, followed directly by a Harley Davidson. You can tell the Harley because it's the one that sounds like a loud, loose, flappy, continuous fart. At just after 4:00 I make a fast high-RPM pass. By that I mean 7-8k RPM.

It doesn't sound anything like this when I'm on it, so I was surprised to hear that my bike sounds like a Sprint Cup stock car at high RPM. I'm quite pleased with the sound, really.

My exhaust is stock, save for a few holes the previous owner punched in the end-plate of the baffles. These holes appear to have been done with a nail. I can upload a pic of that later if anybody wants to see.