950 Unsteady at cruise

my 2013 990 Baja does the same and its fuel injected. it does it more when the bikes warming up

This could be stupid but how about the clutch discs or springs? Just thinking out loud... [emoji2]

Tapatalked @ sgsIV

I'm running the facet to. I've had no issue since changing to the facet pump.

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When things heat up, clogged fuel filters push the fuel pump to its limits. So replacing the filters could cure your problem and save your fuel pump.
Cheers.

i only have 2500 miles on my bike. i wouldnt think that the filters would clog that quick.

That's false.

Normally you have to vent it because they're in a closed airbox setup, and when you open the throttle, vacuum is created inside the airbox and you need atmospheric(ish) pressure as a reference for the slide to operate. If you drop the airbox, or take off the plastic triangles it's simply enough to take off the vent hoses, there is no need for further actions, it'll be just right. This 10' and 11' length vent hose is just plain bullshit, it doesn't matter how long it is unless it doesn't terminate in a place where there is huge positive or negative pressure deviation from atmospheric.
Also an improperly vented CV carb will most likely hold steady RPM well - as the slide eventually will open, but a lot slower than normal - So if it's surging at a steady throttle the problem is something else.

I have no scientific back up for this but I believe the problem is with the FP needles- they seem to have a taper that produces a lean spot at partial throttle opening- cruise range. I think these needles are designed for 0-wot operation and not particularly suited for steady cruise/ 1/4opening

4mm

I'm very late to the party here, and I'm very sure your problem has been fixed by the excellent input from the usual crowd, but I've got to know if this was a Freudian-slip of some sort or a typo.? Or did you literally mean you'd swear a lot as a consequence of the surging???!!!

Cheers... Paul

Don't ask me why I did this, I had the bike up on the table and centre stand and start the engine and put it in the first gear. Back wheel is spinning.

I see the chain travelling on the top of the swing arm, jumps up periodically. This happened even when I open the throttle but less. I got a video of this which I will link here once I upload it.

I am not sure if this is a symptom of an issue with the carb tuning or is my chain damaged. First I thought its not lubed well. But I don't see any dry joints.

I cleaned up the chain anyway with chain cleaner solvent and air compressor and lubed it. It has about 10000km on it.

Repeated the test, its is still doing the same thing.

Video: http://smu.gs/TU7NAQ

Looks normal to me (jumping around while bike is on the centerstand, as there is no load on the back wheel and it's not an inline4 :)).. But maybe your chain is worn out a bit unevenly, and is also a bit on the loose side for highway riding IMO. When you have the uneven ride feeling, try to pull the clutch and see how it behaves. If it doesn't go away it's most likely to be a chain issue..

I agree with Sumi, your 'jumping chain' is pretty much as to be expected. However, towards the end of your video when you open throttle a bit, it absolutely does not sound correct. To me it sounds like it's firing on only one cylinder immediately off-idle.

Are you sure your carbs are clean, the float heights identical, the pump is working well, they are well synchronized and they have approximately the same pilot screw adjustment? Run the bike looking down the intakes to see if the slides are both opening at the same time and to approximately the same height when you crack open the throttle as you did in your video. If not, check the diaphragms, springs and vents. Stop the engine and lift each slide, then drop it. They should both return pretty sharpish, but not crash closed. Most importantly they must both behave in the same way.

If all that is found to be correct, what condition are your spark plugs? Their colour and condition may give some clue as to what's going on. When were they last changed?

Difficult to diagnose remotely, but this should be easily fixable if you work through everything logically.

Cheers... Paul

Today I'm fixing a leak in the rad. The fan plastic shroud has been touching the rad and made a pin hole. Jb welded it.

I will take the carbs out now and work my way down the list and report back.

thx

Please let us know whether that holds.

it didn't
http://www.advrider.com/forums/showthread.php?t=986459

Bummer.

Thanks for the warning.