Delkevic 450mm carbon exhaust - making it more quiet - Honda CBR250R Forum : Honda CBR 250 Forums
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post #1 of 9 Old 09-24-2019, 05:29 PM Thread Starter
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Delkevic 450mm carbon exhaust - making it more quiet

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:s-l400_1569356376241.jpg
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: aco_ecr_1569356698638.jpg
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:IMG_20190923_180820_1569356879556.jpg

Any suggestions really welcomed
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post #2 of 9 Old 09-26-2019, 02:21 PM Thread Starter
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Thought of a twist for the first option - pack the inside of the baffle for extra dampening.

The original baffle is empty inside IMG_20190926_172128_1569517826448.jpgIMG_20190926_172156_1569517848936.jpg

I bought a heat resistant rubber seal - will be a much better fit than a welded washer IMG_20190926_180730_1569518335687.jpgIMG_20190926_180742_1569518359480.jpg

Now just drilling the holes and finding a way to secure the packing inside
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post #3 of 9 Old 09-29-2019, 04:18 PM Thread Starter
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Drilled the holes:IMG_20190929_192332_1569784500316.jpg

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.
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post #4 of 9 Old 09-29-2019, 04:22 PM Thread Starter
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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
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post #5 of 9 Old 09-30-2019, 12:53 PM Thread Starter
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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 😉
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post #6 of 9 Old 09-30-2019, 01:13 PM
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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.

2012 CBR250R Black
Mods:
Racetech springs and emulators, Yamaha R6 shock, Yoshi Rearset Risers, Babyface GP Shift adapter, EBC HH Sintered Front and Rear Brake Pads, CBR600RR pegs, Mirror delete with CBR600RR block offs, Ebay Bar-end mirror, Red LED dash, The2Wheels levers, Homemade Fender Eliminator, LED Blinkers, Tank pads and grips, CBR300R seat, Spider Peak red Grips, Vortex Clip ons, DFC, Delkevic 14' Slip on, Spiegler Braided Front Brake Line,Black Rims
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Big Bore?
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post #7 of 9 Old 11-09-2019, 06:02 PM Thread Starter
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Quote:
Originally Posted by CBR Blaize View Post
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
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post #8 of 9 Old 11-09-2019, 07:28 PM
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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.
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post #9 of 9 Old 11-10-2019, 06:56 PM Thread Starter
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Originally Posted by TrueFaith View Post
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

Last edited by timginter; 11-10-2019 at 07:03 PM.
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