Last night on the freeway, I was cruising at 90ish and the tach read 6K. I tried opening up the throttle and the system started stumbling anything over 6K. So I backed it off a bit, and tried again. But, a little later, I forced it to open up, and it steadily walked its way up in RPMs and speed. I exited the freeway, stopped at the light, and the engine died. I started it back up and took it home with no further issues.
My first intuition is going to be fuel delivery. The bike has 15K+ miles, and to my knowledge, has not had the fuel filter replaced. Is this a good place to start and a likely one? And, with such a large air intake, and the flapper mod done, I dont believe it could be air delivery.
I guess it might be important to say that it has a PCIII. This is just for your brains to choke on.
It surely sounds like fuel, however, clogged fuel filters don't magincally unclog themselves, while you're driving. If you decide to replace it, it's in the tank and you'll have to remove the tank and drop the fuel pump to get to it.
What you're describing can be fuel delivery, ignition, loose/faulty electrical connections or even a glitch in the MAP you're using.
I'd drive it a little more and see if it duplicates the problem. Try to determine exactly when it does it and under what conditions. I'd probably start by disconnecting the PCIII and seeing if it does it, if it continues. If that stops it, it's a PC problem. Make sure the PC is grounded to the battery terminal and not the frame/engine.
As simple as a clean tank full of fuel may solve the problem as well.....
Problems that are that severe and appear that quickly are electrical. But in the case of FI bikes electrical stuff controls the fuel also. I bet you have a bad connection to some kind of sensor or a bad sensor of some type that is changing the mixture or switching to a “limp home” mode. Or possible a vacuum line that is bad. But usually a vacuum line will cause a high ideal.
Start with the basics and don’t jump into thinking big mechanical things. if it ran really good a week ago then don’t bother with plugs and air filters. If it stumbles and runs badly maybe some bad gas or a vacuum line. But other than that I would look at electrical stuff.
It is funny that the electrical is mentioned, such as sensors...reason being, I just did a set of track days and swapped my coolant for water. Well, long story short, I lost the water on the track (my fault) and refilled it later that day. The system would not bleed. If there is an air bubble in the coolant, it may be possible that the temp sensor may be sending a faulty reading to the computer, thus changing the mixture.
I know on my toyota rockcrawler, if the coolant has an air bubble, if the bubble passes by the temp sensor, the reading changes the idling characteristics of the system, and the engine runs funny. But, with the choke on the RC51, I am a little unsure if the temp sensor would affect the mixture on this bike.
oddly enough i have had this problem twice, both were electrical, first it was as simple as a battery cable that came loose, but second the ignition pulse generator wire, going to the computer was halfway cut.
when it was the battery cable it woudl turn off and rack m nuts everytime
when it was the pulse generator, it woudl idle fine then at about 5k it woudl stumble and occasionally die, and since it was half cut it woudl work sometimes, but not always, somethign to look at. also the pulse generator wire is the yellow one that looks like its streched out to reach the whole in the grey connector so im sure it sees a lot of abuse.
those could be your problems or my bike could just be a devil bike that hates me and tries everything to rack my nuts and get me to stop riding it idk but good luck
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'02 RC51
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well, I broke the bike down and swapped the water for coolant and distilled water mixed, checked all my electrical connections and battery terminals, and found nothing loose or cut.
At this point I kinda figure it was something in the fuel. I took the bike out today for 30 minutes, and the temp was 92. I ran it hard on the freeway, I let it build heat in town, and all seems good now.
stumbling, hungry engine
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