hi

I own Honda CBR 125 2014. bike just doesn't feel right. I can't get her above 7k RPM(6k while riding) and she seems like out of power, even tho when u ride her you can feel the compression is good. Today i took her apart to look what's wrong and i got hooked on the injector. she's got a 6-hole injector(i believe so if i counted them right) and the problem is that the injector seems like to give enough fuel for her, but whenever i give her more throttle the injector just stops leaking fuel and you can't hear the "tick" sound anymore, release the throttle and she gives fuel again and you can hear the "ticking"(when i give a little bit of throttle she still works good, but when i give her more it just stops feeding her fuel). Should i look for new injector? my dad tells me it might be oxygen sensor not giving her enough oxygen because once we took the sensor out and the working rythm didn't change at all. Should it be like that? or is it not working, like we think?

 

Have you been through the basics - plug, air etc? Will it rev higher in neutral?

https://cbrforum.com/forum/other-mod...issues-103732/

 

I've checked the air filter it's brand new, fits, works fine. Just checked the spark plug turns out it has too rich air/fuel mixture (it's carbon fouled.) Googled what can cause this and faulty oxygen sensor can cause this. I guess this might be the problem because there's no difference of how she works with or without it. Going to order new one and hope for the best.
(Forgot to mention. When i give her max throttle something starts misfiring, turns out it's the spark plug because it's carbon fouled, and she aswell has very low power, turns out this might be also because of rich spark plug.)


Thanks for reminding to check the spark plug! I was ready to buy a new injector which costs around 70euros, maybe it's the oxygen sensor after all.
(P.S. Beign in neutral or gear changes nothing with RPM)

 

Max throttle uses a pre-set map in the ECU, below max it uses the O2 sensor - so your situation is strange, I would have thought it was the throttle position sensor.

Are you sure no one has messed with the wiring and replaced the O2 sensor with a resistor to mess with the bike fueling to extract an extra 2hp or so?

 

Hm didn't know about that. After i give her more throttle she starts misfiring, maybe thats because of spark plug and the misfires keep messing with her rpms and power? Tomorrow ill try to give her new spark plug.

About the wiring im not sure, you can't see much. Where are the most common places to put resistors? Near 02 sensor itself or somewhere in the wiring?

 

https://www.ozbucketracing.com/build...muterlite.html

resistor mod.

 

Quick update. Changed the spark plug yesterday, changed nothing. Did some more stuff, nothing helped but i tried to disconect o2 sensor. After i disconect o2 sensor i can rev her till 11k (she still hesitates when giving throttle, you can hear missfire but she still gets to 11k), and just drops rpms and stalls. even if you give her more throttle, after reaching 11k it just goes down and stalls. After that it's almost impossible to start her with starter, you have to use battery charger and charge the battery for ~10minutes and then she starts. Put in back o2 sensor she again gets stuck on 6-7k and doesn't go any further. Btw, while riding on lower gears when i get to 7-8k rpm you can feel her sputtering, powerloss untill the rpm falls back to ~5k rpm

 

You seem to be saying (you are not clear) that your battery died during your test - if your battery is dead and your charging system isn't working, then the bike will of course stop. No electricity = no fuel. Have you verified that the charging system is working? The simplest way is to simply measure the voltage when the bike is running - it should be ~14v compared to 12v when the bike is not running.

What's the history of this bike - has it ever worked? I am assuming by your questions that you didn't buy it new?