Running Rich Needle setting

I am running rich on a couple of cylinders and just moved the needles down 1 notch on each carb. will this make a significant difference or should I go 2 notches? They were in the middle position to start out. I just did it tonight but has been cold and rainy here so i won't get a chance to try them for a few days now. I am getting a good clean spark on those cylinders but getting a lot of black fluffy carbon on the plugs. Does this sound like it is worth trying? I have never messed with the needles before but found the article in the filebase that walked me right through it.

I doubt the soot is from the carbs. Probably ignition related. I also doubt that trying to fix the soot by mucking with two of the four needles is the way to go.

Start out by telling us which plugs are sooty...

I originally thought it was ignition related too. It is happening on cylindes 1 and 4. To track it down I swapped the coil wires and with new plugs am having the same problem.

Ok then, bring me up to speed, you put new plugs in and swapped wires? Exactly how did you do the wire swap? Did you take the wires off the 1/4 coil and put them on the 2/3 coil?

Yes that is what I did. I have done the coil repower already too.

1&4 is too durn easy then, I guess... hmmm have you checked your compression? Compression issues are at time, caused by lack of valve clearance. This lack of valve clearance will cause poor combustion which is the root of sooty plugs...

IF your carbs are the culprit (still haven't gotten myself convinced they are), then describe your current jetting, intake mods (pods?) and exhaust mods. Sooty plugs would indicate that two of the four cylinders have richer air/fuel mixtures than do the two inside cylinders. For sake of argument, there are three circuits in your carbs (I have forgotten what type we are talking about)... well four... choke (enrichener really), pilot, mid-range and wide-open. If you have pod filters, switch the filters around... the outside two may be restricting airflow.

If the carbs themselves are the culprits, it MIGHT be a cleaning issue. Don't know how to get more specific as the range that is fouling plugs isn't known. I would start by leaning the pilot mixture and making sure that the fuel level in the bowls of all four carbs is correct and clean the pilot air jet and passage to the pilot jet and back from the pilot jet to the hole on the venturi bottom. The pilot circuit will be your most likely candidate for the sooty issue where the air from the pilot air jet hits the circuit. The pilot air jet (on VM carb) is on the intake venturi edge... there will be two holes; one connected to the main and the other to the pilot jet, most times on the same side as the air screw but not on all assemblies. Get some spray carb cleaner and a stiff wire and have at it. When the pilot jet hole is covered, you should be able to squirt carb cleaner (little straw thing needed) into the pilot air jet and watch it atomize out of the small hole in the venturi bottom. If you can't clean it thoroughly, an ultrasonic cleaning would be the ticket.

This is on my 76 KZ900 I am getting good compression on all cylinders. I will try a thourough cleaning. My jets are 115 mians and 17.5 pilot. I am running a stock air box with a K&N filter with a kerker 4 into 1 with the end cap with no baffle. Later model KZ electronic ignition also.

That would be the stock jetting for a 76 VM26SC. The jet needles should be clipped 5DL31-3. If you are "rich" on two cylinders, I am thinking there may be another cause other than the jetting because the K&N drop in and 4 into 1 should actually be leaning things out a tad. The jetting on the 76 is fairly rich and stock jetting will easily handle the mods you have made. First thing I would do is buy some K&N cleaner and wash out that air filter and re-oil it using K&N Filter Charger spray oil per their instructions. Most folks tend to over-oil and this will "richen" the air/fuel mix. Also use NGK B8ES plugs. What kind of coils do you have and what is their primary resistance? If you use STOCK coils, the resistance may have crept up a bit and you could be getting a little less spark than you should have.