Runs rough and cuts off - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 4 (permalink) Old 01-21-2012, 07:46 PM Thread Starter
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Runs rough and cuts off

Ok fellas, I have been working on this bike for quite some time. As soon as I fix one problem, it seems that another is there to take its place. I have been searching the threads on this and I still do not seem to pinpoint exactly what the problem is.

To keep it simple, the bike is running rough. I have a 2x1 exhaust with a leo vince slip on, K&N filter, and also a power commander but it is not currently on the bike until I can get it dynoed. My issue is this, the bike will run but seems to act like it is being restricted in the low RPM's. I can open up the throttle all the way and nothing will happen except a sputter for a couple of seconds and then it will gradually pick up speed. If I do that a few times, the bike will just shut off. I have a really hard time keeping the bike running at first idle even with the choke on.

So far, I have replaced the spark plugs, replaced the fuel filter, replaced the starter relay, put some fresh gas in the take with sta bil just in case it sits for a while until I can actually ride it. I think it could be the fuel pressure regulator but I am not sure. Let me know what you guys think the problem could be. Thanks.
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post #2 of 4 (permalink) Old 01-21-2012, 08:09 PM
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What did the spark plugs look like when you changed them?
Did the exhaust smell of raw fuel or overly rich?
Any new FI codes reported by the ECM?
If you pull the vacuum line to the FPR, does fuel drip out?
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post #3 of 4 (permalink) Old 01-21-2012, 08:11 PM
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I think you just figured it out. The FPR is a very common part to fail with Honda's. The diaphram usually fails, leaking gas into the vacuum line then on to one of the throttlebodies. They're really easy to check. Lift the tank, disconnect the small vacuum line, and then turn the key on to let the pump prime. If it looks like mine did...
They cost about $50.
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post #4 of 4 (permalink) Old 01-22-2012, 12:45 PM Thread Starter
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Ok well I checked out the FPR. I disconnected that hose turned the key to the on position, to have the pump prime. No gas came out at all.

When I changed the spark plugs, I dont think that they looked to bad but they definitely didnt look like the new ones. The ends looked a little burned but not that bad. The exhaust dosnt smeel overly rich or of raw fuel. No gas came out of the line on the FPR. I do not exactly know how to read the codes or pull them from the bike.

I am still puzzled on this. Could it be this bad due to the exhaust slip on, k&N, and the 2 to 1 conversion? I really have not had a full day of riding this bike. I spend all the time working on it. I am getting pretty close to selling it and buying a bike that I can actually ride.
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