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Coffman exhaust

37K views 72 replies 23 participants last post by  Flash Bantam 
#1 ·

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#5 ·
Coffman slipon ninja 400

Hi,

I'm picking my bike up tomorrow after the long ass fucking wait (1.5 weeks) :grin:

I'm thinking about purchasing this slipon -
https://www.ebay.co.uk/itm/Coffman-...150622?hash=item33e722d09e:g:iukAAOSwzpFa2TRN

Anyone know if It's the same as for 300 where you have to drill the hole or am I just imagining things?
I like the sound of it on the 300 and anyone know if it should make the sameISH noice for the 400 if not better?

Appreciate any thoughts and suggestions.. (tight budget on exhaust due to buying the bike and gear + 2 piece suit)

Thanks in advance! :smile:
 
#7 ·
Hi,

I'm picking my bike up tomorrow after the long ass fucking wait (1.5 weeks) :grin:

I'm thinking about purchasing this slipon -
https://www.ebay.co.uk/itm/Coffman-...150622?hash=item33e722d09e:g:iukAAOSwzpFa2TRN

Anyone know if It's the same as for 300 where you have to drill the hole or am I just imagining things?
I like the sound of it on the 300 and anyone know if it should make the sameISH noice for the 400 if not better?

Appreciate any thoughts and suggestions.. (tight budget on exhaust due to buying the bike and gear + 2 piece suit)

Thanks in advance! :smile:
I have one on my 400 and I actually like the sound, direct fit as well. It’s on the louder side but sounds nice.
 
#12 ·
https://youtu.be/QjoAercbIEg

Here’s a video, sorry that it’s a bit rushed. YouTube is still processing the higher resolution so if it’s bad quality at first then that’s why.
Thanks for the upload man!

I ordered mine off of ebay today.. So excited to hear it in person, read reviews about the coffman slipon for the ninja 300 and people say It sounds absolutely awsome!

:grin::grin::grin:
 
#14 · (Edited)
Hi,

Been riding with my coffman slipon for about 60miles now, thing sounds awsome and I couldn't be any happier.
Constant backfires which sounds awsome and a way deeper and nicer sound imo.

Thing only cost $230, I know it's just a "PIPE" though.

Anyways, to my question. I tried taking the baffle out which is held in place by a snapring which I took out but the baffle still won't give in and come out. I did exactly as people do on the ninja 300 coffman baffle removal but mine won't go for some reason...

Anyone who rides with a baffleless coffman slipon who could point me in the right direction?

Thanks, love from sweden :grin:



Managed to get it out after using alot of force, that thing was stuck good!
 
#20 ·
For whatever its worth, and I've not seen dyno charts to prove or disprove yet, but these smaller motors typically like some back pressure.

Running a wide open exhaust, or close to it may actually result in some loss of power as compared to stock.. Just something to consider. :2cents:
 
#21 ·
Yes I can vouch for that. I lost mid range power on both CBR250 & 300 by adding a freer flowing slip on with less back pressure.
You didn't need a dyno to work it out, it was that noticeable. If it did add any top end power then that wasn't noticeable. The CBR's are a single though and don't rev so high, 10,500 RPM redline from memory.
Possibly more to be gained in top end power on the N400.
 
#23 ·
Just to add to this. Backpressure is not why you lost power. It’s the lack of scavenging from too big or short of a pipe.

Think of it as a straw vs water hose. If you blow the same volume through each, the straw will have higher velocity and pressure than the hose. However the hose might have zero pressure because it’s too big and low flow for the given volume. Now add in exhaust pulses. If you have too big of a pipe you loose velocity (momentum) going through the tube and it doesn’t flow well.

There’s a size limit when it comes to exhaust. You want a diameter that doesn’t restrict flow, but also that the momentum of the exhaust is still moving fast enough to create a negative pressure behind it to pull the next pulse through the tube. Make sense? Also rpm has to be taken into consideration. That’s why people notice the loss of low rpm and a slight gain at high rpm. Aftermarket pipes might be too big for low rpm but they might be just right for the higher rpm. It’s because the factory pipe is a compromise of low rpm effeciency and high rpm restriction.
 
#25 ·
Good info. I would like to add that I never got either of my bikes tunes to suit the pipes and on relfection it was probably more low to mid range loss rather than all of the mid range.
I wasn't bothered overly though as I was changing the pipes more for weight, looks and sound reasons in that order. Not performance.
 
#34 · (Edited)
Oh my..they have one with a GREEN Tip... Stainless Steel ceramic coated black Shorty Exhaust, Kawi color Aluminum Tip... that is not to shabby if ya got 230.00 laying around..


Found this sound clip video in red tip..



I really like that Green tip with the bike...
 

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#35 · (Edited)
Oh My Gawd... My lil bike has grown up.. 20 minute install and now I wait a week while it rains(again), to hear it in action... sigh.. but here is a small sound clip right after easy peasy install.. I am pleased! Amazon: https://amzn.to/2OR84BB





EDIT: Weatherman lied and roads are dry.. First Ride around the block with the new Coffman's Slipon muffler.. Sounds lovely....

 
#36 ·
#39 · (Edited)
it's just louder with insert in... it is much quieter than your average Harley if that helps...
to "me"..in looks and sound it is worth every penny.. DB meter 80-84 .. Harleys with after market are usually around 95+ DB..
 
#41 ·
So Fuby....I have watched your videos on the Coffman exhaust.. Now, that you have had some time with it, are you still liking it?

I am NOT looking for the loudest. In fact something marginally above the OEM would be fine for me. But, that $230 price and look of the pipe is sure attention getting.

Curious to know how you feel about it now.
 
#42 ·
So Fuby....I have watched your videos on the Coffman exhaust.. Now, that you have had some time with it, are you still liking it?
Welp... My Ninja is under covers till the spring time now.. But I love the Coffman..it sounds to "me", what this Bike should sound like coming from the dealer.. it is loud enough to hide the lawnmower sounds from the front of the engine and still quiet enough not to offend my ears.. I been around a few Harley's in my days.. this doesn't even rate to that noise level.. I been waiting to see how L337 liked the add on header he purchased and it seems that failed to make a difference in performance.. so I will be content with just this slip on .. it seems to be well made and should last a long time.. I always use the baffle.:grin::nerd::grin:
 
#48 ·
I totally forgot to make a follow on video. I need to design a laguna baffle to make my bike pass tech at some local tracks. I'll probably wait to make another video until I get that figured out... Honda Magna is a great daily. I'll be posting some racing footage at the end of the month.
 
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