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-   -   Delkevic 450mm carbon exhaust - making it more quiet (https://www.cbr250.net/forum/cbr250-parts-accessories/68729-delkevic-450mm-carbon-exhaust-making-more-quiet.html)

timginter 09-24-2019 05:29 PM

Delkevic 450mm carbon exhaust - making it more quiet
 
3 Attachment(s)
Hi everyone,

I put a Delkevic 450mm carbon slip on after my stock exhaust got totally rusty last year. I love the low rumble, but I'm looking to make the exhaust more quiet.

I'm not much into performance side - I just liked the looks and the sound from the videos was great - exactly the low notes I was looking for, just much louder than on videos.

Delkevic sent a longer baffle (and I bought a spare one to tinker around), it helped a bit, but it's still loud.

I was wondering if someone had similar experience or any ideas.

I was thinking about 3 options:

1) Weld a washer around the end of Delkevic's original baffle to seal the hole between it and the exhaust. Then drill holes in the side of the baffle so the exhaust gases are forced into the baffle and out through it, instead just around it and straight out.

2) Weld two smaller baffles together and pack them for a homemade version of this:Attachment 41307
Then put it in the pipe before the can of the silencer. I couldn't find one narrow enough to fit so it would have to be a homemade version.

3) Something like this: Attachment 41309
Pack around the existing baffle origonal doesn't have holes), try to squeeze it in and secure the packing so it doesn't get blown out. Not sure that would work with how the exhaust pass around Delkevic's baffle and straight out of the exhaust, though.

The exhaust is a bit tricky for conventional stuff with all the angles:Attachment 41311

Any suggestions really welcomed

timginter 09-26-2019 02:21 PM

4 Attachment(s)
Thought of a twist for the first option - pack the inside of the baffle for extra dampening.

The original baffle is empty inside Attachment 41313Attachment 41315

I bought a heat resistant rubber seal - will be a much better fit than a welded washer Attachment 41317Attachment 41319

Now just drilling the holes and finding a way to secure the packing inside

timginter 09-29-2019 04:18 PM

1 Attachment(s)
Drilled the holes:Attachment 41327

My 8mm drill bit gave up after a whole length of top and bottom holes 😕 I had another one, 6.5mm, but that struggled after 4 holes and just deformed later. I ended up with the whole length of top-bottom holes and a few left-righ.

********************, I'd rather all 4 from the back of the baffle as far as the drillbit went so the sound had more packing to travel through. I have another long baffle - I'll try it with that one, wonder if there'll be a difference

I put the packing in and wedged a piece of "W" shaped metal in, hooked on the last top and bottom hole, to keep the packing from flying out.

timginter 09-29-2019 04:22 PM

Wow! I'm really surprised with the effect! I measured the bike idling - 107dB a metre behind the exhaust before the mod, with just the long baffle in.

83dB after 😮 Still 1 cylinder 😉 Really happy with that reduction, though

timginter 09-30-2019 12:53 PM

Well... Heat resistant wasn't that heat resistant - melted and blew away after around 20 minutes of riding...

Back to square one, proof of concept confirmed, though 😉

CBR Blaize 09-30-2019 01:13 PM

Cool to see your idea work. I think im gonna have to do something similar to mine. I like the weight reduction but it is a bit too loud.

timginter 11-09-2019 06:02 PM

8 Attachment(s)
Quote:

Originally Posted by CBR Blaize (Post 686461)
Cool to see your idea work. I think im gonna have to do something similar to mine. I like the weight reduction but it is a bit too loud.

Thanks. I just got a crush gasket seal, outer 48mm, inner 38mm - I'll check how to fit it to seal the can end and I'll take some photos. Effect should be the same with some thermal paste

TrueFaith 11-09-2019 07:28 PM

I've had a Delkevic CF "slash cut" slip-on for 2 seasons now and I love it. Don't forget that some slip-ons "mellow" their sound and become a lot less raspy and loud as they age. That's been my experience with my Delkevic. You seem to be putting far too much effort into getting a sound and volume level that you could get by just riding it and letting it develop it's own character. And these Delkevics will definitely do that over time.

timginter 11-10-2019 06:56 PM

8 Attachment(s)
Quote:

Originally Posted by TrueFaith (Post 686639)
I've had a Delkevic CF "slash cut" slip-on for 2 seasons now and I love it. Don't forget that some slip-ons "mellow" their sound and become a lot less raspy and loud as they age. That's been my experience with my Delkevic. You seem to be putting far too much effort into getting a sound and volume level that you could get by just riding it and letting it develop it's own character. And these Delkevics will definitely do that over time.

I've had mine for about 16000 UK miles now - not sure it will get any more character 😄 I like the sound, the low notes when idling or going at a steady speed / downhill - they are great. It's just plain too loud for me, especially the farting pops when accelerating or going uphill - the can is just too straight-through.

A few dB down and it will be a great exhaust for me. And I just like to tinker - win-win.

Anyways - I'm a lemon - I ordered the wrong gasket... not sure why. The baffle is actually 30mm (outer) and the end pipe is 49mm (inner). I found a stainless steel washer 30mm x 50mm online - I'll file it down a bit when it arrives and just weld to the end of the baffle - should be a nice tight fit


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