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Discussion Starter #1
Long time lurker here. You guys have helped me heaps in the past.

I know there are many posts about this already but none have helped.

I seem to be having a fuel issue with my bike which is a 2004 CBR600RR with 36xxx I'm on the clock.
If the throttle is fully open the bike losses power but if I back off it gains more power.

As per other threads, I have done numerous things to attempt to fix it. I have put new spark plugs in, I have had the injectors cleaned and most recently I installed a brand new OEM fuel pump assembly which cost a fortune at $643 in Australia but it hasn't helped at all. While the tank was off, I was able to check that there were no kinks in any of the fuel hoses.

I do have a slip on exhaust installed but this issue was happening pre installing the exhaust (but before I had tried doing anything to fix it).

Does anyone else have any other suggestions for what my issue my be? I have been putting off doing further track days until my bike is fixed and am really keen to get back out there.

Thanks in advance!
 

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I am also having the same issue. I'm wondering if the throttle position sensor may be the culprit. For me it's happens from 3/4 throttle up to full.. Back off a tiny bit and power returns. Feels like a electrical issue to me. I'm changing air filter and plugs to start. May clean the fuel pump also. I'll check all hoses.
 

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I haven't at this point. I have the airbox removed atm as im doing the pairs removal. The cut is so definite on the position of the throttle that i really think its must be electrical... Bike pulls hard right before and then has a unchanging loss in power beyond 3/4 throttle. Visibly the nozzles look mint. Any idea of the voltage needed to activate them? What method do you recommend to clean them?
 

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I haven't at this point. I have the airbox removed atm as im doing the pairs removal. The cut is so definite on the position of the throttle that i really think its must be electrical... Bike pulls hard right before and then has a unchanging loss in power beyond 3/4 throttle. Visibly the nozzles look mint. Any idea of the voltage needed to activate them? What method do you recommend to clean them?
Im not sure on the voltage. The reason I asked is because I bought a zx once and it did pretty much what your describing, at high rpm. Took it back to the shop and they took them out and put them in a cleaning machine for injectors supposedly. There is however a video floating around of a guy who runs carb cleaner through the injector while puting 12v source onto it. Maybe something to try if your short on funds or can't find a spot..

Sent from my VS990 using Tapatalk
 

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Ok thanks for the suggestion. Ill get the nee filter and olugs installed and see where im at. I saw that video.. Looked promising.
 

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Discussion Starter #7
Hi, thanks for the replies.

I did clean all 8 injectors and I have just tested the TPS with a multimeter. The TPS appears to be in good working order also.
 

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Discussion Starter #8
Just in case anyone else is having these issues, I was speaking to the workshop who cleaned my injectors for me and they mentioned they didn't ultrasonically clean them. They just ran a cleaner through them. So I pulled all 8 injectors out again and took them to a place that did ultrasonically clean them. One of the secondary injectors was only flowing at roughly 75% while all other injectors were fine. After being ultrasonically cleaned, that injector is now at roughly 96% and my issues are fixed!

TL;DR - the injectors caused it. Make sure the injectors are ultrasonically cleaned.
 

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Quick update.. So i bought a used fuel pump and secondary injectors from a track bike with half the mileage of my bike. Installed both and the bike is a beast. Pulls hard to redline. Running some seafoam just to clean things up a bit more but its running perfect. Cleaned the strainer of the new unit for good measure (it wasnt really dirty but i figured i had it available and couldn't pass up the opportunity).

Bike is a totally different animal.
 
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Glad you guys figured it out. Next time you may want to find a local guy with a dyno. It's more cost effective to have them run it a few times and see what your ignition and A/F ratio are doing before buying parts. I've had a similar problem with mine and it turned out to be starving or running too lean. Tuned in some more fuel at that RPM range and it cleared the problem.
 
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