Is this the same as a stock CBR 125 downpipe inside?

RockandGrohl · Nova Slayer Joined: 19 Feb 2013 Karma :

Bit of a gory title, but can't be arsed to think of anything more eloquent.

Got a new downpipe for the CBR in my hands, it's got some strange shit on the inside of the can-end, last time I put a downpipe on a CBR it was aftermarket and took 10mph off the top end - bad times!

https://imgur.com/a/pOMCJ

Have a look there. Ideally if anybody else has a CBR 125 (04-10) with stock downpipe fitted, I'd like to know if the can end of your pipe is the same, thank you!

dydey90 · World Chat Champion Joined: 01 Oct 2013 Karma :

That appears to be a non-return valve, I believe.
I don't think mine had one in, but the original had completely rotted away and I replaced it with a stainless one.
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This post is probably not serious and shouldn't be taken literally.
Past: CBR125,~~ER6f~~ NINJA 650, ZZR600 Current: VFR750

RockandGrohl · Nova Slayer Joined: 19 Feb 2013 Karma :

bumparoni

RockandGrohl · Nova Slayer Joined: 19 Feb 2013 Karma :

Just an update, this pipe went on my bike 2 weeks ago.. and it did take 10mph off my top end.

It's a result of these cheap, Chinese shit pipes. Basically where the pipe thickens in the middle.. it doesn't actually thicken, it's the same narrow length all the way through.

To explain, revs climb nicely all the way to about 7-8K, and this is where the power band of the CBR 125 is. But here the engine really struggles to deliver power with this Chinese downpipe on.

If I hold my hand over the exhaust and rev, I get air pushing back all the way to this 7-8K revs, then it almost totally drops off.

In terms of practical application, I can accelerate to 60mph in the same time it takes to accelerate to 70mph on a stock downpipe. I can not go any faster than 60mph on this fucking downpipe.

Accelerating to that speed is also greatly reduced. Going from 40-50mph is a struggle, 50 to 60mph is an absolute crawl.

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

Are you sure. What gear are you in and are you on a flat.

RockandGrohl · Nova Slayer Joined: 19 Feb 2013 Karma :

RockandGrohl · Nova Slayer Joined: 19 Feb 2013 Karma :

I took a picture of the stock exhaust, it's got no valve or baffle or anything inside it, and it the pipe widens a fair deal more than the chinese knock off. It's definitely a problem with the pipe. If you hold your hand near the exhaust you can feel good back-pressure when you climb the revs but as soon as you get to about 6-7K, the air pressure just drops out. This matches up to what I feel on the bike, acceleration up to 6-7K, then when I'm about to hit the power band where the revs are at like 8K and above, the bike doesn't seem to accelerate, but it keeps revving up.