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Discussion Starter #1
Hello all, I'm new to the forum, not new to bikes.
I looked around a bit online and on forums to see if anyone has had this problem before, but I couldn’t find anything specifically matching my case
My sisters 2003 CBR600RR is giving her problems and I cannot solve the issue.
6500 miles, full Yoshimura, stock airfilter, PCIII. Unknown map
Before it warms up (hit the road after 1min idling) it runs like a beast, no sputter whatsoever.

After warming up(been on the road for 5min or so), it begins to idle rough, and takes off roughly. On a normal take-off, it’s comparable to bouncing off the rev limiter randomly. Its bouncy and embarrassing. It FEELS like it’s not getting gas.

With a PCIII plugged in, this sputtering lasts from idle to around 3200rpm

If I turn up the PCIII all the way in the low range it helps by moving the clear up zone to about 2800rpm

I disconnected the Power-Commander and the clear-up worsened, moving from idle to about 38-4000rpm. -That makes me think its insufficient fuel

AND it has a dead spot around 11k-rpm where if the throttle is wide open it will just die like it hit a brick wall, but if I back off the throttle and roll on it will continue to pull.. If a bit grouchy about it

Useful bits:
Plugs/air filter-Clean.
Injectors/fuel lines/fuel tank/filter-CLEAN. I'm 100% sure
Charging system-good.
Grounds/terminals/connections all over-clean secure.
All 8 injectors are firing.
All 4 plugs are sparking.

Checked with propane all over to make sure there was no vacuum leaks/change in idle-Nothing.

The fuel pump is building enough pressure to spray a light mist all over the place if I just barely loosen the fuel line after shutting off the bike.

I have had this bike apart so many times and it seems spotless. It’s to the point where I feel like maybe it’s a sensor or something beyond my ability to diagnose with wrenches and elbow grease. I would like to avoid taking it to a dealership or mechanic at all costs.
Any help is greatly appreciated
 

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Check the fuel pressure regulator. Mine behaved in a similar fashion when it was worsening. They go out over time and just get replaced with another OEM part. YouTube how to check if it's bad. Easy check by pulling the vacuum line.

Also, mine did not leak but was still bad.
It's an older bike and has very little miles so that's my guess.
 

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Discussion Starter #3
On the 03 600rr there is no external FPR. If it exists, it's built right into the fuel pump. There is no circulating return-line like most older bikes. I don't understand why the pressure would be insufficient at lower RPMs, but work fine when it's wound up.. Unless it's too much pressure. The fuel pump would be an expensive process of elimination step, I may just have to try it though. Thanks for the tip :thumb:
 

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One thing you should do is find out what fuel map the PC is running.

You didn't mention if you have any codes, or flashing FI light? Check your TPS connector?
 

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Discussion Starter #5 (Edited)
Ah, good technical point to include. No it isn't showing any codes.

I have removed the PCIII just to eliminate the possibility of a screwy map, because I dont know what he tuned it to. My sister does not ride to a level where that PCIII performance will be missed. I could be wrong but I don't think the Yoshimura alone will cause this without being tuned to it, so I think it will be ok without the PC for now

Another technical point I should have originally included, this sputtering problem developed recently within the past two months or so. So it hasn't been there since storage. I dont see why the PC map(s) would have changed? Regardless, I disconnected it.

Development: I noticed it is starting to build up a bit of oil droplets at the front-tip of the airbox where the line from the valve-cover connects. It's not a lot but its even getting specks of it onto the velocity stacks. Is it sucking too much? like an engine vent is open elsewhere? (oil level is normal in the window and always has been) or is that small bit normal.

I was hoping for something like a bike equivalent of a cars PCV valve gone bad..

"If there is something wrong with a Honda car it's the CV axles or the PCV valve." I would find it tremendously amusing if it were the same on this bike :rotfl:but I dont think I get off that easy this time

This hose blowing oil is separate from the pair valve lines, which I am considering deleting while I am in there

I'll make sure the TPS is plugged in tight as well, but I might not have time to get it all back together tonight. All secondary opinions are appreciated, I'll keep you updated
 

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Discussion Starter #6
Ok update: I disconnected the pair valve. Plugged the middle and right valve cover ports, plugged the front air-box port, and hooked (with an extended hose) the left valve cover port up to the rear right air-box port (point being it’s more protected from oil splatter)
With this configuration the bike ran GREAT.. for like 10minutes…until I noticed there was oil coming out the filler cap and realized the engine was under enormous air/gas pressure. (I didnt know they weren't reeded' vents for the crank case, now I realize they let air into the exhaust) I thought they flowed the other way. Either way it makes no sense and I didn't know what I was doing. Feel free to call me an idiot

Back on track

So, I hooked the middle valve cover port up to the air-box and plugged the left and right pair-valve ports like everyone does. Bike runs like CRAP


Plugged the air-box ports completely (left and right valve cover ports plugged)and ran the middle valve cover port to an independent vent filter. Bike runs like CRAP.


Hooked the pair-valve/valve-cover ports back to stock configuration. Bike runs like CRAP


Maybe it was just a coincidence that it ran good for about 10-15 minutes while the crank was under pressure. Maybe not. I am completely lost. The bike is spotless under the plastic. Connections are good.

The Power-Commander is completely disconnected from power, from the injectors, and from the TPS. It's now stock as far as fuel management.

Assuming the wrong configuration in vent hoses was the reason it ran correctly- WHY would that be?
 

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my low end sputter turned out to be a reg/rect. was reading ok on multimeter (low end of ok) but was actually bad, causing weak spark.
 

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What do I know, no one wants my advice, but that said...I respect your diligence and attitude. I gather that needs to be said often in case you're originally from CA and insecure as a man? Inside joke, never mind.

if your exhaust valve is adjusted too tight, it will cause running issues after it's warmed up and in some cases, won't even let the bike run. Cold good/ warm CRAP can be just too tight a valve lash. I'm just another douche bag unable to see your bike in person. What do you have to lose to get that out of the way, compared to a trip to a service shop? Cheap, fast, gets it out of the way and just as random as all the other suggestions, IN MY OPINION.

It was never tipped over before? How's those plugs? I had a Ninja that ran like crap until I replaced the plugs, it was tipped over at some point before I got it. It had 4500 miles. I took it to a shop and they went for the plugs right away, problem cleared up similar running issues, although temp wasn't a factor.
 

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I'm no technician but here's my $0.02 of experience.

I cleared up similar issues with my 954 by replacing fpr and plugs. Bike ran great for a few months then symptoms came back, but not as bad. I found that one plug seemed to loosen up overtime. A quick retorque fixed it.

Also, I don't know if tight spots in my chain contributed to shotty performance issues but changing these three parts out is what fixed it all.
 

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Discussion Starter #10
CH676 : There is no FPR on the 03 CBR600RR, but it may very well be the fuel pump, I have replaced the plugs as well. They are tightened down well. Im pretty sure the chain is free flowing, ill take a look at it next time I can get my hands on the bike :)

Blunt: I'm not sure what you're talking about, if you're serious, or just in a bad mood. The exhaust reeds were tested bypassed and in stock configuration, it didn't make a difference. The exhaust valves have not been touched since the factory, and at about 6600 miles I don't think that is an issue. Spark plugs are one of the first things that should be checked. They were the first things that were replaced/gapped/torqued. This isn't the first time I have worked on a bike bud. Suggestions like check the plugs, check the injectors, check the fuel pressure, check the compression, check the voltage ect, are all basic given steps that should have already been eliminated before asking for help on a forum.. In My Opinion. I'm asking for help for things that are out of my hands or that I don't understand, like checking/tracing problems to sensors.

FeelFree: That was one of the first guesses. But like you said, it checked out on the multimeter. Hmm. That would probably be the next process of elimination step that is within my reach :thumb:

Its really spotless and I am stumped. The CBR has been parked and my sister is borrowing my 00 TL1000R for the moment to just get out and ride until she can get her tax return and take the bike to a shop.. I'll see if I can get my hands on a RegRec so I know I'm at least safe there before taking drastic measures(aka take it to a shop). I wont be working on it for a few, I'll let you know if anything changes when I can get to it again.
 
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