Spark Plug Coloring

[MPittma100]

These pictures are of a spark plug currently running in a 1979SF.

Carburetor jetting is stock - all jets. Exhaust is stock. The ignition coils are Dyna and the air filter is K&N.

Question: What are your thoughts on the color? Is it lean, rich, or just right?

The fuel being used that is still in the tank is 90 octane E0 (non ethanol). This may or may not have affected the coloring. I have not looked at the plug coloring with E10 (ethanol) fuel. 90 Octane is the only available octane that I have found E0 in so far.

I leave E0 in the tank during the off season (winter) and run E10 regular normally.

Bike gets 35 MPG.

MP

[bikerphil]

Hard to tell the color from the pics Mike, but either gray or light brown/tan is ok, white would definitely be too lean.

[motoman]

They're similar to others i've seen that are using aftermarket coils/irid. plugs.

[DGXSER]

Does not look sooty or ash covered, light grey color, might be just a tic lean, but nothing to lose sleep over. Like Phil stated, color is hard to see in a pic close enough to diagnose plugs.

[BA80]

Looks pretty close to good Mike. Like Don said, a tick lean.

You might try raising the main jet needles one notch at a time and see if you get a better tan. They should be on the center notch if they haven't been messed with. You can move the clip down (which will raise the needles) a total of 2 notches still if so.

I went up 1 size on all my main and pilot jets because mine was running a little hot and I had about the same color plugs. Kept the needles on the center notch. It helped quite a bit but I probably could have gone 2 sizes up.

Running the Mack 4 into 2 exhaust. Everything else pretty much stock.

Didn't affect the mileage noticeably.

[MPittma100]

Plug color

Looks pretty close to good Mike. Like Don said, a tick lean.

You might try raising the main jet needles one notch at a time and see if you get a better tan. They should be on the center notch if they haven't been messed with. You can move the clip down (which will raise the needles) a total of 2 notches still if so.

I went up 1 size on all my main and pilot jets because mine was running a little hot and I had about the same color plugs. Kept the needles on the center notch. It helped quite a bit but I probably could have gone 2 sizes up.

Running the Mack 4 into 2 exhaust. Everything else pretty much stock.

Didn't affect the mileage noticeably.

The needle clips are in the standard position. And I agree, a tic lean but not too lean. Next time I clean them I may richen the needles one notch.

[D0wn5h1ft]

The needle clips are in the standard position. And I agree, a tic lean but not too lean. Next time I clean them I may richen the needles one notch.

You'll more likely than not lose gas mileage. They say run rich to avoid overheating but I wouldn't touch it if I were you. Check your timing and advance with a timing light as that drastically affects gas mileage [happened to me].

[MPittma100]

Timing

You'll more likely than not lose gas mileage. They say run rich to avoid overheating but I wouldn't touch it if I were you. Check your timing and advance with a timing light as that drastically affects gas mileage [happened to me].

I checked the advance a couple of years ago. Actually had the advance unit out. Vacuum advance was also working. But it has been long enough that I should check it again.

[Bonz]

Great looking plugs, 'nuf said!

[TADracer]

They look fine to my eyes. Look at the body around the threads and there is no soot build up there which is one of the first places it will build up if you are rich. Also I can clearly see the line where the flame front ends down the length of the insulator which means you have a good heat range plug. I would leave it all alone.

[motoman]

The needle clips are in the standard position. And I agree, a tic lean but not too lean. Next time I clean them I may richen the needles one notch.

Don't have that option, but from what I've seen reported here in the past for the early carbs adjustable metering rods has been the standard middle position for clip.
To richen things up a bit in the mains cruisin' LD rides, don't forget the ole' trick of the teeny-tiny washer under the clip instead of lowering clip one position. That'll give ya' approx. half a step.