fueling problems? sp1 - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 45 (permalink) Old 08-25-2013, 02:46 PM Thread Starter
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fueling problems? sp1

Hi there,

So I'm having some issues. trying to get some guidance.
I have a 01 RC, I bought it 5 months ago. It has Jardine slip ons, power commander, and k&n air filters.
So its been running rich from day one, but now its running rich, running hot like 210-225, was running around 190 when I got it. Its back firing, and stuttering when I give it gas (hesitating, almost like a misfire). its an intermittent problem. Been going on for a few months. It just happened like an hour ago on a mountain ride, then everything was fine after I turned around to go home.

I was just thinking I needed to retune, but now Im think it has other problems.. can anyone chime in with some ideas?
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post #2 of 45 (permalink) Old 08-25-2013, 03:00 PM
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This has been discussed a lot mate. its more than likely gonna be your K&N filters. RCs dont like them one bit and dont run properly

Honda SP1.5 owner
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post #3 of 45 (permalink) Old 08-25-2013, 03:33 PM
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Replace the fuel pressure regulator, search the threads for the test sounds like your culprit...even if it passes the test they still fail and cause the same symptoms. Also they are not expensive if it happens to be your PC...

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post #4 of 45 (permalink) Old 08-25-2013, 06:23 PM
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1st disconnect your Power Commander to see if the performance improves. Bad PCs cause this too. While you are in there, you can do as Nobody stated, FPR check

See post #8


Keep us posted on your progress.

The very first schoolbook that was written had God all over it. --Dave Mustaine
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post #5 of 45 (permalink) Old 08-25-2013, 10:57 PM Thread Starter
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I used the search feature. Couldn't find a thread that was quite like mine. I am going to order a new fpr tomorrow. So I'll get back to this thread next week after install. Good call on disconnect the pc. A buddy was tellin me the MAF might be dirty and be causing these problems too, so I'll clean that as well. Thank you guy.
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post #6 of 45 (permalink) Old 08-29-2013, 08:56 PM
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I was just going to post up about the fuel pressure regulator. It sits on the end of the hard fuel line circuit on the top rear throttle body. It has two rubber hoses on it one returns fuel to the tank the other is a small vacuum line that returns to the two main intakes. I assume they create vacuum to actuate the fuel pressure regulator. Mine fpr allows fuel to bleed by it into the vacuum lines and returns into my cylinders causing them to flood. I have one on order. $40 I think.

On my Tuono I had a problem more similar to yours. Turned out the banjo bolt coming off the fuel pump on the bottom of the tank was squashing my fuel tank vent line causing it to starve the motor and run exceptionally hot as you try to keep it running in an extremely lean condition. If it does it again, pop the fuel tank lid and see if it returns to normal. Or if you have the tank up look at your vent hose and see if it is pinched shut somewhere before it does it again.

Your fuel pump should squirt 6.4 ounces of fuel in ten seconds. That's volume only not pressure which requires you to hook up a fuel pressure gauge to your tank. If you take the fuel return hose off the pressure regulator and plug it so fuel doesn't leak out of the tank. Then install another hose attach it to the fuel return nipple point it into a collection container you have already measured and marked for 6.4 oz you can turn the key on position. the fuel pump is set to prime for two seconds. When it stops toggle the engine kill button off and on again to create another 2 second cycle. Repeat for a total of 5 primes should equal 10 seconds and you should have 6.4 oz min in the container.

I'm a newb to the RC51 but am reading the manual like crazy. I highly recommend it.
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post #7 of 45 (permalink) Old 09-09-2013, 11:48 PM Thread Starter
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Okay so I changed out the FPR today with a OEM one. took it for a spin, did not solve my problem. After that got home disconnected the power commander, rode it to class, no problem. On the way home it was doing it again. It being cutting in and out while giving it throttle (3rd gear freeway). like it was hesitating. it was like 67 degrees, and light fog on the way home. The problem happens in the heat too (85 degrees hard riding twisty roads) .

The bike has 22,500 miles on it. I have no idea about any past maintenance. The only thing I have done is oil change (rock oil synthetic), coolant (rock oil coolant), swapped out the old chain/sprocket. That's about it.

Any more ideas before I drop it off at the mechanics? I would rather fix the problem myself rather than spend $85 an hour to have someone else do it, if I knew.. Thanks.

Last edited by mikehawk; 09-09-2013 at 11:51 PM.
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post #8 of 45 (permalink) Old 09-10-2013, 09:22 AM
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You could take the filters off as someone else suggested.
Also, running hot and running rich are two separate things. One is coolant related and one is fuel related. Is your coolant reservoir at the proper level? How does the coolant look. Does your exhaust have any smeel to it, or does it smell like it is running really rich? What do the plugs look like? they should have been changed at least back at 16,000 miles. Might want to look into doing those as well. bad plugs would make the bike sputter and seem like it's running rich.
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post #9 of 45 (permalink) Old 09-10-2013, 09:43 AM
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Happens cold or hot, all over the place. Doesn't sound like fueling to me. Could be an intermittent or loose power or ground if all gears. So many people trace it to loose battery cables, for example. Or a worn harness, etc.
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post #10 of 45 (permalink) Old 09-10-2013, 10:16 AM Thread Starter
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I forgot to mention I did the plugs about 1k ago ago with NGK spec'd plugs. After further reading, I found those temps to be normal operating temperatures. I did a coolant flush, and refill last week - overflow tank is full. I'm no longer worried about the temps.

My main concern is the fueling. It's super unsafe, and unreliable. ,the pipes smell rich, my buddies if they are behind me say its pure raw fuel smell. The filters are going to get swapped to OEM this week, but I don't think my k&n would be giving this effect.

I'll check the battery/harness tonight when I get home. Could it be my injectors are stuck open?
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