Sooty plugs on 1 & 4

Just pulled my plugs after not checking them for the last 1000 miles. The plugs on cylinders 1 & 4 are sooty, but 2 & 3 are tan. The carbs are VM26's and it took me a while to get them dialed in for the setup in my sig. They are all set up exactly the same right down to the number of turns out on the air screws. I also synced them a couple of months ago. The bike runs great thru the entire RPM range and even idles smoothly at 800 rpm. I've heard of people running larger mains on the inside cylinders since they don't cool as well, is this a good idea? Maybe I should go down a notch on the mains in the 1 and 4 carbs only, or maybe I just shouldn't worry about it and clean the plugs more often :whistle:

I would look at ignition not carbs. 1-4 are on same coil. Coincidence that both are sooty from carb issues not too likely. Inspect plugs, wires, coils, condensers and points.

I had the exact same problem. You could do a coil mod as listed on another part of this board or what I did was take the coil in question off take a dremel tool and clean all maiting surfaces everything then take apart every bullet connector and in turn grind/clean all of those and blow them out. I am sure the coil mod works as many people have done it but I wasn't sure if my problem was fuel or ignition. For what its worth I did both coils put new bolts through them dremel tooled everything to a shine:lol: even resoldered the two leads on the coils and cleaned the ballast resistor connections. Sorry I didn't read what type of bike you had but I'm sure this will be of some help if not just a shortcut.

I'll tell you I had it at a bike shop and they couldn't find anything it is very elusive:S

Sooty plugs mean an incomplete combustion. If your jetting is OK on 2/3 and the same on the outside cylinders that are sooting up, there is little chance that the air/fuel mixture is wrong. An air/fuel mixture oriented towards too much gas would be the cause of plugs sooting due to carburetion but I think your problem would be elsewhere. The other two most likely areas where there could be problems would be compression and ignition. Since the problem is on two plugs that are linked in the ignition, that seems most likely. Since your coils have sufficient power through use of the coil repowering upgrade, I would look at a coil whose impedence is higher due to age, bad connection of the plug wires to the coils or perhaps bad boots. The easiest way to start troubleshooting an ignition problem of this nature is to FIRST swap the 2/3 coil for the 1/4 coil. See if the problem moves to the 2/3 cylinders.

Thanks, I should have thought of the coils. They are fairly new as are the plug wires, doesn't mean nothings wrong with them though. I'll make sure the power connections to the coils aren't loose or something, then I'll try the coil swap.