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Discussion Starter #1
Hi there, I have just installed a new Delkevic 450mm long exhaust and I am experiencing increased vibration levels through the seat and rear grab handles. (I would hazard a guess this is why the standard exhaust is a heavy item to adsorb the secondary vibration from the engine)

I have loosened all the clamps and set the position of the slip-on several times with the same result.

Has anyone experienced bulb, battery of computer related failures from vibration, when fitting a replacement slip-on or full exhaust?
 

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Many cheap exhausts are not packed properly and need doing straight away.

If it sounds raspy and not deep its a sure sign its not absorbing the resonance (is that the correct word?)
 

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Discussion Starter #5
The exhaust properly wont have packing, there is a central perforated tube that runs the length of the can (this is normally wrapped in packing), however the DB killer is a 250mm tube with a round dome on the end (rather like a bell end), when this is inserted into the exhaust it effectively separate the can into two parts. Exhaust enters the end of the can and is forced through the perforated tube into the outer can and then re-enters the perforated tube to exit the exhaust. If there were packing the exhaust would effectively be blocked when the DB killer (baffle) was inserted.
 

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stock exhaust is heavy for other reasons..
honda wouldnt choose to place a heavy weight
on one side rear 'to reduce engine vibrations'..
my lv slip-on produces zero vibrations at
its mounting point, never mind further
up potential vibration pathways..

something isnt right..
first thought damping at mounting points,
such as rubber around cannister and
between mount and mounting bolts..

probably wouldnt hurt to contact manufacturer,
could be something simple known to them..
 

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Discussion Starter #7
Mounting rubbers all good, i think it maybe because its the longest (quietest one they do @ 450mm long), the end of the slip-on is oscillating as the mount bracket is on the first 20% of the pipe and needs to be in the middle. I am going to remove it for the time being and contact the manufacturer for there opinion.
 

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The exhaust properly wont have packing, there is a central perforated tube that runs the length of the can (this is normally wrapped in packing), however the DB killer is a 250mm tube with a round dome on the end (rather like a bell end), when this is inserted into the exhaust it effectively separate the can into two parts. Exhaust enters the end of the can and is forced through the perforated tube into the outer can and then re-enters the perforated tube to exit the exhaust. If there were packing the exhaust would effectively be blocked when the DB killer (baffle) was inserted.
It's hard to believe that an aftermarket can wouldn't have some kind of packing material... if that's true, it would certainly explain the increased vibrations.
 

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That's strange I have the exact same one. Mine is the 450 mm stainless steel version. I don't have any weird oscillation at the end or more increased vibration. Just a deep rumble. After a little over 2k miles on it still great. I think with smaller companies the QA is always gonna be hit or miss. Just an observation, though.
 

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oscillation should indicate movement both sides of
its mounting strap/nut, provided the strap/nut and
its mounting point [footpeg bracket] are solid..
header pipe if undisturbed should be solid,
leaving midpipe attachment suspect..

on mine [lv] midpipe is welded at cannister
and was a good tight fit to end of header pipe..
ie, no potential for movement required for
oscillation..

manufacturer will ask if header pipe and
footpeg bracket are solid and secure..

even without packing etc it should not
oscillate, provided good fit and mounting..
 

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Discussion Starter #12
Ok pictures are worth a thousand words.

As the sketch of the pipe, with the baffle inserted the gas has to pass through the perforated tube twice, if there were packing the exhaust would be effectively blocked.

As the installed pictures the clamp is in entirely the wrong position to stop the end of the can oscillating with the vibration from a single cylinder engine. the clamp needs to be nearer the centre. The clamp position is not a problem with the short 200mm and 350mm length pipes, the 450mm is just wrong.

I cannot verify this as i can only hold the can while the bike is on the stand, as i cannot use the throttle and touch the pipe when riding the bike.
 

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Ok pictures are worth a thousand words.

As the sketch of the pipe, with the baffle inserted the gas has to pass through the perforated tube twice, if there were packing the exhaust would be effectively blocked.

As the installed pictures the clamp is in entirely the wrong position to stop the end of the can oscillating with the vibration from a single cylinder engine. the clamp needs to be nearer the centre. The clamp position is not a problem with the short 200mm and 350mm length pipes, the 450mm is just wrong.

I cannot verify this as i can only hold the can while the bike is on the stand, as i cannot use the throttle and touch the pipe when riding the bike.
You sure that can is the right one for a CBR250R? I went on their website, and I didn't see a 450mm listed amongst the various options for the 250R. Just from an appearance standpoint, that can looks way too long for the bike.
 

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After looking at your picture it's not all the way down. Mines a bit higher. That may explain why you have your problems. Mine isn't that low compared to yours. Yours is lower than the picture on the website too. Mine hangs like the one on the website. I also just noticed your exhaust tip is not like mine or the picture on the website maybe wrong can? There is an angle that points the tip straight back not straight like the can.
 

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Discussion Starter #17 (Edited)
OK, another image attached, i did notice that the top of the hanger bracket was touching the bottom of the foot peg bracket, I have bent is slightly so vibration is not passed directly to the foot rest, however only make a small difference.

Regarding the exhaust system, you can buy from eBay uk the 450mm version in either straight or angled tip versions 450mm Oval Straight Outlet Stainless Steel Exhaust Silencer CBR250R MC41 11-14 | eBay and yes the 450mm version is not on there website. (also all the picture on the website are Photoshop)

I am going to loosen the clamps and rotate the intermediate pipe to see if i can change the angle of the pipe, also i have noticed that there is a 50/50 split on users that mount the exhaust hanger on the outside of the foot rest bracket or the inside, mounted on the inside is as per Delkevic photos.

I am waiting on a replacement gasket and am going to mount the OEM exhaust to see if the vibration is still there, if it is then back to Honda for advice, if not exhaust may be back on ebay this weekend.
 

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Yeah I decided to look afterwards and did notice two different designs. Also its pretty clear they are photoshopped but it still is what it should look like. My hanger is higher than yours is what I meant. So it's not as down low like yours. Good luck.
 

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Perhaps Delkevic never meant that silencer to be fitted to our bike and the one you bought off ebay was cobbled together by the seller? I bought mine directly from Delkevic and it included a gasket.

It may be an Idea to contact Delkevic for their advice. I don't think that Honda will help you with the installation of an aftermarket part.
 

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Discussion Starter #20
The exhaust is from Delkevic UK, they have sent me a replacement gasket (and a multi-tool as an apology). After refitting the OEM exhaust the vibration is reduced, putting weight to the theory that the heavy OEM exhaust damps out some unwanted vibrations, not unlike the bar-end weights in the handlebars.

That i am going to submit to is that may be the vibration was always present, the delkevic straight through chugging noise matches the vibration of the engine exactly and is mentally amplifying the vibration, where as the muted OEM exhaust noise is soft and scattered and does not seem to oscillate in sympathy with the engine.

On a passing note the OEM seems to produce a smoother power response from the engine and my seat-of-the-pants dyno suggests that the Dellevic power claims are only all noise.

If anyone in the mainland UK wants it i will accept and ship for a £100 saving you 25% on the ebay price.
 
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