CBR125's, Rusty Downpipes and you.

[RockandGrohl]

Ok so I feel like with my multiple CBR 125's, multiple exhausts and many thousands of miles I'm an expert on this subject. I'm hoping that when someone searches "CBR 125 rusty downpipe" and comes here from Google I can help them out, but I guess this is generally good advice for anyone not really clued up on Exhausts n shit.

CBR 125 Downpipes like to rust for fun. You open a pepsi near a downpipe and it starts to rust. The stock downpipe is thin. It's unprotected low-grade steel, and Honda must think their 125 riders only ride in hot, dry environments.

Unfortunately I live in England and we get about 2 teaspoons of Sunshine per year so there's many times when it's rainy and you have to drive around on those skinny tyres sliding everywhere.

I had a 2005 CBR 125, I noticed it sounded a lot louder than usual. Then the exhaust snapped... In two places. I got it welded together but it didn't last long and it snapped again. Honda only sell the downpipe and exhaust together in one part, it's £250. I looked on eBay and found a downpipe that claimed to be "OEM standard replacement" let me tell you, this is a crock of shit.

They look like this:

https://i.imgur.com/Kko5G7e.jpg

Looks the standard part, right? Looks good! Seems sturdier. This is an abomination to all 125cc motorbikes everywhere. Why?

https://i.imgur.com/Ex8DQQP.jpg

It has that stupid baffle in there. You can barely see it, but it's in there.

You see how the diameter of the pipe from where it connects to the cylinder block is quite narrow? But it widens up? Bullshit, it's that narrow all the way down the length of the pipe. The outer thicker part is just to keep it quieter.


So what's my beef? Well you connect it up to your bike and standard end-can, it seems to work, you start the bike up and it sounds normal. You ride it and that's when you notice it. A CBR 125 Power band is around 7K revs. You get to 8K revs and you stop accelerating, but the bike continues to rev. In every gear. The result is that a CBR can happily do 70mph on a flat, and it's good at accelerating up to 40mph rapidly.

With the new pipe, you're lucky to get 60mph. Every gear you accelerate then plateau till you rev into the next gear, and it's all due to the pipe.


The problem is, these pipes look identical to OEM, apart from the lack of the heat shield by the right footpeg and underneath that heatshield on the stock exhaust is a Honda stamp. This isn't on the Chinese one.

Oh yeah, I contacted a few places who sell these and asked where they originate from. All from China. We all know the quality of Chinese-made bikes, don't we?


So what do you do? Well, yesterday I fixed my problem. I bought a Black Widow Downpipe. It arrived last Tuesday and it looks the part. £71 off their website, which is significantly cheaper than the £110 I paid on eBay 2 years ago to replace the downpipe on my 2005 CBR.

It fits in perfectly, every part of it is adjustable. It comes in two parts.

This is on my 2010 CBR, fox light Fuel Injected model. Downpipe snapped after 5 years (though previous owner had it stored in Garage and was a fairweather rider)

I managed to get a downpipe for £30 off a chap on the other 125cc motorbike forum. He claimed it was a standard part and I bought it only to find out it was the Chinese tat. I installed it anyway as I didn't have a pipe and same issue, 10mph off top end, struggling to accelerate.

A common way to know if you have one of these pipes is to hold your hand over the exhaust and rev the bike slowly, you should feel good backpressure but when you get to 7K revs the air will die down.


Right away, accelerating away in 1st gear, I can feel the front wheel lift up again, I can feel the bike continuing to gain pace right the way to the redline, in every gear. I managed to do 70mph again.

Here's a comparison of the two exhausts. The Chinese pipe was pretty much in new condition and had a few months usage (and it hasn't even been particularly wet this spring either)

https://i.imgur.com/jAnWDEw.jpg

It's hard to see because of the reflection but the pipe I bought is significantly thicker, it's got no stupid baffle in it. It's a little louder than stock but most importantly it lets the engine properly exhaust the gases!


So guys, if you have bought a CBR 125 and it seems sluggish, check the downpipe.

If you already have a chinese one, get rid of it ASAP and drop the £70 on a new Black Widow one. Christ I probably seem like a shill. I'm just a happy customer.

[rhys99]

[Nobby the Bastard]

[Commuter_Tim]

[RockandGrohl]