1984 KZ440 smoking black from right cylinder.

Hi All,
Just wanted to get a little insight into the possible causes for my 1984 KZ440 smoking black from the right cylinder. The left cylinder spark plug is running a nice tan colour and the right one is running black and sooty.

Here is what I have done so far: cleaned carbs and set float levels to spec, set valves to spec, replaced plug wires, plugs and caps, tried swapping plug wires, but the right side still smokes and the left side still runs clean--so I don't suspect the coil.

Any insight you good folks could offer would be greatly appreciated.

Choke butterfly or idle circuit.


.

Pretty sure the choke butterfly is OK, but I will take a look at the idle circuit. Thanks for the suggestion.

Are you burning any oil at all? is it a significant amount of smoke or just a small amount? Does the engine temp make a difference? Found out the hard way my bike is leaking oil past the valves when it gets good and warm. Ended up overheating my engine a bit from low oil now the valves are leaking a bunch. Went from a little to a lot of black smoke but all from leaking past the valve guide seals. Initially I couldn't even tell it was burning oil until I did a 200 mile continuous stent and lost a bunch of oil over time . The primarily leaking cylinder spark plug looked black and suit covered while the other looked nice and peanut butter colored initially as well. Bike ran great, wouldn't have known it was even burning oil . I just thought it was rich on one cylinder until I really ran it hard for an extended period.

Doesn't seem to be burning oil and the black smoke is just a puff here and there, especially on a throttle blip. Before I cleaned the carbs it was running a little sooty on both cylinders, which makes me think it has more to do with the air/fuel mixture. But thanks for the heads up--I will keep an eye on the oil level.

Nebr_Rex wrote: Choke butterfly or idle circuit.


.

A special thanks to Nebr_Rex for putting me on the right track. When I cleaned the carbs I somehow overlooled the idle air screws. When I checked the air screws, sure enough, the one in the right carb had a lot of deposits on the air screw needle. After cleaning the air screw needles, the bike runs great.