running rough at low speed??? - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 10 (permalink) Old 08-09-2016, 07:53 AM Thread Starter
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running rough at low speed???

running rough at low speed???
Chaps, I'm a newbie so have very little knowledge of this bike, ps its also the first bike ive owned with fuel injection.
so i bought the bike this weekend and took it out for the first time monday night,the problem is its running real lumpy at low speed, it has a power commander fitted (pc3)
Im thinking ,because the bike has done very few miles in the last 2 years (300miles and 9miles respectively) that it could be just old fuel causing the issue?
im a very competant mechanic and have 4 other bikes that i tend to service myself so would the injection system bung up like a carb? if so how easy is it to tear apart and clean?
was thinking about sticking some sort of fuel system cleaner thru it and doing a few miles to see if it clears itself, taking it to the classic TT in two weeks so want it to be tickety boo for then.
details are 2000 sp1, 18 k miles all standard apart from power commander and yoshi slip on silencers.
thanks
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post #2 of 10 (permalink) Old 08-09-2016, 03:24 PM
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They are bad below 3000 rpm it does help lowering the gearing so at 30mph you are higher up in the rev range
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post #3 of 10 (permalink) Old 08-09-2016, 05:12 PM
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try checking your fpr, they tend to go bad on these bikes.

lovin' my little torque monster.
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post #4 of 10 (permalink) Old 08-10-2016, 01:52 AM Thread Starter
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FPR ????? what is this?
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post #5 of 10 (permalink) Old 08-10-2016, 02:30 AM
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Fuel Pressure Regulator
There is a thread on here if you search for it that will walk you through it.

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post #6 of 10 (permalink) Old 08-10-2016, 02:36 AM
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This one should get you where you need to be.
https://www.rc51forums.com/forums/65-...regulator.html

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post #7 of 10 (permalink) Old 08-10-2016, 03:34 AM Thread Starter
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thank buddy, will do!
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post #8 of 10 (permalink) Old 08-11-2016, 09:18 AM Thread Starter
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ok so i checked the fpr as described in the other post, and it seems fine. have ordered one anyway so if it goes sideways i will be ready, Ive taken off the "yoshi" pipes that were on it as they turned out to be cheapo blue flame cans with HRC badges on, ive tested the pcIII thats on it and its mapped for standard pipes/airbox, so hopefully this could be the issue? will test it again on Saturday after ive done the oil and filter change.
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post #9 of 10 (permalink) Old 09-04-2016, 03:20 PM
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I'll throw out my $0.02 to say that below 3500 RPM, the bike is difficult to tune for fuel. The rough nature is most likely a fuel issue or at least the majority of a fueling issue.

W/O a PC and aftermarket exhaust, the bike will run extremely rough because of incorrect fueling. With a PC, you can smooth it out but fixing smooth roll-on becomes difficult.

In most cases, jerky, rough or surging is caused by a lean fuel mixture. Adding fuel at the lower RPMs should help but since the RC is a twin, you have the two independent cylinders to try and tune which means it will be very difficult to manually fix without dyno time.

If you want, manually add some fuel in those lower rpms for both cylinders. I run the stainless yosh slip-ons and below 3500, my fuel map is adding around 10% in the various 2% - 5% throttle position cells. Above 3500, it removes 10%+ (-10%)

I run the PCV with autotune and noticed that the bike does not run smooth with an AFR above 13 in the 2% or 5% cells. Just my own personal experience.

If you do stepup to the PCV at some point, keep your PC3. There's a problem with the PCV and RC51 that causes an RPM bounce. Keeping the PC3 in and adding the 5 to it will filter the problem. (Do a google search for RC51 rpm bounce for more info)

Long story short, proper fueling at those low rpms should fix the problem.
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post #10 of 10 (permalink) Old 09-04-2016, 06:49 PM
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I'm being lazy and don't feel like typing.

Quote:
Originally Posted by pirks View Post
They are bad below 3000 rpm it does help lowering the gearing so at 30mph you are higher up in the rev range
Yes

Quote:
Originally Posted by Luckyadam12 View Post
This one should get you where you need to be.
https://www.rc51forums.com/forums/65-...regulator.html
Yes

Quote:
Originally Posted by philsward View Post
I'll throw out my $0.02 to say that below 3500 RPM, the bike is difficult to tune for fuel. The rough nature is most likely a fuel issue or at least the majority of a fueling issue.

W/O a PC and aftermarket exhaust, the bike will run extremely rough because of incorrect fueling. With a PC, you can smooth it out but fixing smooth roll-on becomes difficult.

In most cases, jerky, rough or surging is caused by a lean fuel mixture. Adding fuel at the lower RPMs should help but since the RC is a twin, you have the two independent cylinders to try and tune which means it will be very difficult to manually fix without dyno time.

If you want, manually add some fuel in those lower rpms for both cylinders. I run the stainless yosh slip-ons and below 3500, my fuel map is adding around 10% in the various 2% - 5% throttle position cells. Above 3500, it removes 10%+ (-10%)

I run the PCV with autotune and noticed that the bike does not run smooth with an AFR above 13 in the 2% or 5% cells. Just my own personal experience.

If you do stepup to the PCV at some point, keep your PC3. There's a problem with the PCV and RC51 that causes an RPM bounce. Keeping the PC3 in and adding the 5 to it will filter the problem. (Do a google search for RC51 rpm bounce for more info)

Long story short, proper fueling at those low rpms should fix the problem.
And yes.

These are what I'd recommend as well.

Mine acted in the same way before I went with the PCV and AT, even with a custom map.

If yours is not a custom map made for your bike I would start there, as long as everything else is sound.

James
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