Good afternoon all.

I have a Honda CBR125 from 2004 that, after getting to operating temperature, acts like it has an air passage. I can't figure out what it is, as soon as I accelerate, it seems to get stuck at 4000RPM. It has had the valve clearances set, it has brand new gaskets, I have tried another carburetor, a new spark plug, the diaphragm is fine no tears. I don't know what it could be, I'm getting sick of the bike.

Thank you,
Anselmo

 

If you have access to starting fluid spray, that can sometimes locate a vacuum leak.

 

Sorry for the late reply, I'll give it a go on the weekend.

 

Is this other carburetor you tried brand-new from authorised Honda dealer?
If not, you've got TWO carburetors that need full restoration work.

Also check fuel-pump flow-volume.
And measure & test TPS.

 

The carburetor is a known good working one, even if not brand new.
Throttle Position Sensor? Could you send a pic of its location?