Loading up..!

[jomur]

Hey Guys, Bike runs good at higher RPMs, but sitting at stop light it starts to run rough. when i go to take off it feels like it going to die, have to add a lot of gas and feather the clutch. replaced plugs couple weeks ago and it ran better, but now its doing it again. spark plugs in 2 & 4 look perfect, 1 & 3 are black and soutty.(but not wet). is this just a sync problem ? Just bought the bike in may, and im trying to wait till the fall to rebiuld carbs

[mro]

First

I'd check the plug caps and wires,
Sync and adjust the pilot screws, then re-sync.

If still a problem then I’d pull the carbs.

mro
BTW, have you done all the regular maintenance plus
clean/check all the wire connections?

[BigRed]

Definately sounds like carbs to me. Your new plugs probably worked well until they carboned up. If you brush off the carbon, then it'll probably run well again for the same amount of time as it did when they were new. As stated above, I'd synch, adjust your mixture, and re-check your synch. You may want to check your float heights first.

[Rickrod3]

Hey Guys, Bike runs good at higher RPMs, but sitting at stop light it starts to run rough. when i go to take off it feels like it going to die, have to add a lot of gas and feather the clutch. replaced plugs couple weeks ago and it ran better, but now its doing it again. spark plugs in 2 & 4 look perfect, 1 & 3 are black and soutty.(but not wet). is this just a sync problem ? Just bought the bike in may, and im trying to wait till the fall to rebiuld carbs

My bike does that too.
Sometimes it runs like a top. except fot the stumble at 3K Other times it behaves as you described.
My plugs are on the lean side.
I've ordered a colortune thats my next step since I have synced them.
I'm starting to suspect pick up wires.
I have checked them for the hour glass effect they do not stretch when I pull on them.
I could feel a slight bump where the corner if the coil touches them.
I won't cut them unless I'm they are broken.
Going to check them with a amp meter.

Rick

[dbeardslee]

Jomur - Did you colortune when you set the mixtures? Does it act the same way after cleaning the plugs, or does it exhibit the same symptoms? You'll get conflicting opinions on colortune, but I find mine indispensable for adjusting carbs. Along the lines of checking plug caps and wires, you might run the primary and secondary resistance tests on your ignition coils. I've seen 'bad' coils do a pretty good impersonation of a slow circuit carb problem. Only takes a few minutes to check. If you haven't cleaned your electrical connectors, that might be a good idea as well.

[CatatonicBug]

If it were me, I would just take a few hours and a couple cans of carb cleaner, and pull the carbs. You never know what kind of junk might be in there, and even the tiniest piece of junk can mess with the fuel circuits. It sounds to me like you have a dirty idle circuit and since the rest is running fine, you probably don't have a major issue in there. Just a good cleaning, then sync and colortune, I bet the problem will disappear.