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Apr 12

Posts: 2

unclePancho says:

CBR 125 Problem with engine

Hey guys, my first post post here :)

I have a problem with my beloved CBR that I cannot seems to solve by myself. Starting from the beginning, the downpipe of the bike started to rust, and at one point it snapped completely. I have bought a replacement downpipe, fitted and sealed it in the place, but now the bike kind of lost its 'power' (yes its a 125, still fun to ride, gotta learn on something and this bike is most reliable 125 I've ever been on). 

Before anything was broken the bike was able to pull 75-80mph only struggling with acceleration at 6th gear between 6-7k revs. Now after fitting the new downpipe (replacement of a stock pipe, with no restrictions according to the shop) thebike struggles a lot - in any gear goes up to 5-6k revs and almost stops accelerating although the revs go up. I can also feel with my hand that when in neutral I open up the throttle the revs go up steadily, but when it hits around 6 the pressure of gas coming out of silencer kind of drops (just like when you blow the air with your mouth and run out of air). Also the top speed dropped to around 50-55mph max in 4th gear (5 and 6 just make it slow down).

Is there anything i can do with this pipe (drill it or something)? I cant really afford another one, and I really need and want to ride the bike :upset:

Thanks in advance guys...

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  • Posted 3 years ago (29 April 2012 13:43)

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Mar 09

Posts: 8936

jaffa90 says:


Welcome u..............o,if the new down pipe is the same spec as the one took off, i suspect you`ve upset rust in the can causing a restriction.

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Jan 08

Posts: 7549

kcmc says:

Honda CBR 125 Year? Model?

Hi UnclePancho and welcome to the site:smile

Am with Jaffa90 on this,take the Exhaust silencer off and see if you can bang  and shake the the debris out,if possible also use a air line to blow it through at high pressure.

Good Luck


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Apr 12

Posts: 2

unclePancho says:


I took the silencer off completely for polishing, before I've done it I tried shaking it around and slightly banging it with piece of wood, and it seems like there is nothing really in it (unless its a big lump stuck together).

I'll try and run the bike without silencer to eliminate it from the list. I've also been told that the engine sounds like it's running with no oil (there is still just below 'max' level, changed 4k miles ago).

Do you guys know if drilling holes in the very last bit of downpipe (where the silencer bolts on) and taking out the U shaped metal plate from there might make a difference?

EDIT: it's a 2006 carb model.

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