Charcoal black spark plugs

Here is a question for you experts. I have a 1981 Yamaha XJ 650 Maxim. The question is when I put new plugs in a few days later they are charcoal black.

A little bike history
Cleaned carbs( step by step from this site ) And I bench synched them
New oem coils and spark plug caps.
New Spark plugs
New oem carb boots and intake boots.
New MAC exhaust ( the one that was closest to stock)
New Air Filter

I bought a colortune and started with the air mixture screws 2 1/2 turns out. When I started to tune it the colortune cable from the plug to the cap melted and came out of the plug and is un useable now.

At 2 1/2 turns out 3 of the plugs are charcoal black. While the number 2 plug is perfect.

At 2 turns out the same 3 plugs are in the same condition

At 1 1/2 turns out the same 3 plugs are in the same condition

At 1 1/4 turns out the same 3 plugs are in the same condition.

I am not going to go any more for the fear of breaking something and have went back to 2 and 1/2 turns out on all of them
I know the norm should be 2 1/2 to 3 out. So I have now Idea what is going on. Also each time I moved the airmixture in I change the plugs to new plugs. And after about a week the bike begins to pop and back fire. Then I pull the plugs and put new ones in. Any help would be appreciated I am stumped

Thanks
nsosh5

 

Are you cleaning the plugs between adjustments? Also, before Rick gets a hold of you, adgust them in degrees, not fractions. As Rick will surely chime in here shortly and tell you, the sweet spot will be withn the thckness of the edge of a dime or nickle, NOT fractions of a turn.

 

Yes I put new plugs in after each adjustment and ride for about 2 days and checked them again. And also if you are going that lean there should be a dramatic difference in the plugs and there is not.

 

You need to set-up cooling fans if the Bike ain't moving while you are doing the tuning.
Trying to tune-up an overheating bike is a waste of time and not good for the engine, at all.

Most of XJ-Nation is getting Tuned-up, one bike at a time.
Everybody is beginning to realize the necessity of having perfectly cleaned and prepared carbs on the bike before beginning any fine tuning.

It sounded like you were getting close and got off track.
What stage are you at, at the moment ... and where are we going next?

Preset your Pilot Mixture Screws to just shy of 3-Turns out.
Lets see what happens with the Plugs.
We'll do what we have to ... to get you dialed-in.

 

Right now they are 2 1/2 out but I will put new plugs in and put it closer to 3. When I get my camera back I will take pictures of them and post it. Thanks for the Reply rick Ill get back on and let you know what happens

 

how do I shrink the pixels down to put a picture on here

 

just host it on photobucket or flickr, they'll give you code to just pop directly into the forums! as well as they have handy minor editing tools, like cropping and resizing =)

 

Here are what the plugs look like at 2 1/2 turns out.

 

Thanks switch.

 

Are the pics good enough

 

Not really.

But, its nice to know you know how to put a picture in with the Post.

 

have you got a 'macro' button on your camera (for very close pics)

 

No I dont know how to make it any clearer.

 

tough to see, but rich is a word that comes to mind

you are reving to bike to ~5k rpms right?

What jets were in place when you cleaned?

and what air filter did you put in<brand>? is said air filter clean and flowing<not restricted>?

what is the spark plug you're using? Numbers specifically

 

Yeah rev to 5k They are the stock jets that are in there. And a k&n air filter was in there when I bought it. I bought a recharge kit for it and cleaned it. And I am using a NGK bp7es spark plug. I know they are running rick and when I adjust the idle screws it hasnt got better. So I am thinking about going to a hotter plug.

 

I dunno, it seems like hotter plugs would just mask the problem... somehow the bike is getting more gas (or less air) than it needs. are all the jets stock? does the bike run different whether it's hot or cold?

 

Yeah all of the jetts are stock. I am out of ideas I don't understand why adjusting the airmixure made no difference.

 

I think at 5K pilot screws don't make as much difference since you're getting more fuel from the main circuit...

it's possible that float level is too high.. also if the choke cable is too tight, the enrichment plungers might not be closing all the way.

does the bike foul the the plugs while idling?

 

I measured the floats before reassembling the carbs and The choke doesn't touch the plungers until you apply the choke. And it does foul also if the bike is idling. Thanks for the help man I am really stuck if you have any more ideas. I will try anything...

 

Ok stupid question. You said you cleaned the carbs. Are you positive you got the air jets in the top properly? I know the Haynes manual shows them reversed. Not sure if that would cause your problem.

 

I put the jets back into the same spot that they came out of. It is to the point that I know the carbs like the back of my hand. lol Thanks bill if you think of anything else please let me know.

 

can you kill a cylinder by turning its pilot screw all the way in?

if so, turn it in all the way, then out just to the point where the stumble disappears, plus a nickel-width of a turn. rinse/repeat for the other 3... see if it fouls the plugs then.

 

Thats the thing I turned them all of the way in and it is still fouling the plugs.

 

If you have had them all the way in and are still fouling the Plugs ... there has to be some Fuel getting into the Combustion Chamber from some source just to keep the Bike running.

This would lead me to wonder if (Possibly) the O-rings at the Bottom of the Pilot Mixture Screws are place right.
If they got flipped and the washer is below ... you wouldn't have good control of the Mixture.

Same if they are worn-out. They would just let Air and Fuel pass-by and not respond to Tuning very well.

Then, there's the possibility of Oil doing the Fouling from Rings or Valve Seals needing service.

 

I didn't think about the o rings I will pull them off tonight and check for it tonight. I will let you guys know the verdict as soon as I get done. Thanks!!!