Weird - fluttered at low RPM

[supperduc]

I was in traffic yesterday so spent a lot of time in first gear flying at 5 miles an hour for a good 30 minutes.  Anyhow, my bike started acting kinda weird.  It fluttered when I engaged the clutch at low rpm and almost felt like the throttle cable is slipping or jerking.  I could actually hear this tsk tsk sound coming from the throttle body.  This only happened at around 1000 - 2000 rpm and when the clutch (first gear) is engaged. The problem, however, went away once the rpm passed 2k rpm.

I rode her again this morning and the same thing happened.  This time I was just pulling in a gas station for gas and the engine temp was only around 180F.

Truly appreciated your expert advice! Bike is a 2007 S4RS, Stock ECU, Zard Pipes, 1400 miles.

[motoxmann]

bad batch of gas?
is the grip slipping on the throttle tube?
in need of a valve adjustment? or timing belts need to be re-tensioned?
tps need to be reset?
unless you are running an open airbox with no air filter, I would find it near impossible to hear an abnormal sound from the throttle body, unless what you heard was an air popping sound which usually only occurs when there's a misfire

[supperduc]

Closed air-box with air filter. Hard to describe the sound but the very faint tsk tsk noise sounded like something mechanical is slipping. I can actually feel a slight jerk on the hand grip (the grip is not slipping on the throttle tube). 

[Dirty Duc]

I don't think any Duc is happy below 2000 RPM.  On mine, the chain will slap and it lurches in a most alarming way.  I get around it by choosing a different route rather than riding in 5mph traffic for very long.

For short distances, you can keep the RPM up and slip the clutch while controlling your speed with the rear brake.

If there is truly no way around riding in lame traffic at super slow speeds, I would just gear it ridiculously low so I could have a few more RPM at those 1st gear travel speeds (makes wheelies even easier, also)

[supperduc]

Thanks for the assuring response. I live and work in the Northern Virginia area so have to deal with spaghetti bowl traffic. There are no alternatives.

I like to let the bike idling and use the clutch exclusively during stop and go traffic (yep, I can crack walnuts with my bare fingers). Strange thing is, this problem didn't happen until yesterday. I did change the timing belts, oil change, and coat the gas tank with Caswell epoxy liner a few weeks ago but doubt that any of these maintenance/repairs would cause the fluttering problem. 

[Dirty Duc]

You also don't have very many miles on it.  Mine is still developing new sounds... sometimes they go away...

Double-checking belt tension wouldn't be a bad idea.

You might also inspect the charcoal canister lines at the throttle bodies for cracks or proper installation.

[supperduc]

Will double-check the belt tension on the next opportunity. I removed her charcoal canister the day after I bought her   

[Dirty Duc]

in that case, check to see that whatever solution you used to plug those holes is still intact.  Some of those vacuum plug things are less resilient than I have expected.

[supperduc]

Checked the belts' tension and the vacuum plugs (aluminum bolts). Everything looks fine. hmm...

   

[motoxmann]

check sparkplug gaps. thats my best guess besides possible bad batch of gas.
I do however also agree with the above mentioned low mileage still accumulating new sounds that can come and go

[supperduc]

Found the problem. It was a bad sparkplug wire. Thanks!

[ducpainter]

Thanks for the assuring response. I live and work in the Northern Virginia area so have to deal with spaghetti bowl traffic. There are no alternatives.

I like to let the bike idling and use the clutch exclusively during stop and go traffic (yep, I can crack walnuts with my bare fingers). Strange thing is, this problem didn't happen until yesterday. I did change the timing belts, oil change, and coat the gas tank with Caswell epoxy liner a few weeks ago but doubt that any of these maintenance/repairs would cause the fluttering problem. 

If you are willing to sacrifice some top end different gearing will make the bike a whole lot easier to ride in traffic.

You might consider a 14T front sprocket if you haven't already changed it.