Spark plug black as night

[mikojh]

Currently my spark plug is jet black with grey on the small little piece of electrode thing. Obviously the mix is running to rich. What can i do to try and rectify this as this could be responsible for power/performance problems im experiencing at high speed. So far i have checked for leaks and checked the air filter both are fine. BTW I never having problems starting the bike nor does the bike ever die just runs like shit at high speed. I also did a compression test the other day which was 140.

In my user manual for the bike it also says if plug is of an excessively hot appearance on a standard spark plug to try a different one. Worth looking at? Does hot appearance mean black? Theres another plug recommended for a wet appearance why cant they just give clear colours.

Hot=Black?

[fatpies]

A too hot spark plug would be powdery white.

Have a look here and compare

https://i176.photobucket.com/albums/w170/SDHonda153/DensoSparkPlugChart.jpg
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"It's easy to attack and destroy an act of creation. It's a lot more difficult to perform one"

[MickC]

Rich mixture or your burning oil, any smoke from the exhaust?
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Previous: CG125,XS250 (converted to 400),Z250A, GPZ550, Norton Commando, XS500, 78 Laverda Jota, GPZ1100,Harris bonneville, XV750 (mono shock),TR1

[cb1rocket]

if its black its running rich. If everything else is stock and standard then try running a hotter plug. That usually means going down in a number for an NGK plug, ie BR8 would then become a BR7.

So yes your plug is running a rich and would explain the crap high speed running to some extent.

[temeluchus]

Was it running ok beforehand and has gotten worse?

Made any changes to the bike?

Few possibilities:
Blocked and dirty air filter (check this first)
Jet too rich
Float height incorrect(flooding)
Float needle worn or dirty(flooding)
gasket/seals in the carb worn
Something blocking the inlet to the airbox.
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[Fizzer Thou]

I am not sure what bike the OP is riding but if the bike is standard there should be no reason to change the spark plug model.

If the bike is carbied,check to make sure that the choke mechanism is switching off completely once the engine is up to temperature.

But if the bike is fitted with fuel injection,items like a coolant temp sensor going faulty would tell the ECU that the engine is not hot enough to lean off the mixture and so constantly run the engine rich.I have diagnosed this fault before and is easy to check if you have a service manual or Haynes/Clymer.
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[mikojh]

[cb1rocket]

that looks just right except the picture is out of focus

[Thorn]

That plug looks OK tbh!

If you want an example of a bad looking plug on a 125, see here: https://thoronir.net/photo/Skyjet_Rebuild2_Plug.jpg


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Skyjet SJ125-26 (Dead) || Yamaha FZS600 (Dead) || Kawasaki ZX-9R C2

"Everything you touch turns to disappointment."

[Shaft]

If anything, it looks like it's burning a bit hot.

On my 'puter, the centre ceramic seems bright white (should be a nice biscuit colour) and the outer electrode appears to be misshapen, like it's been spark eroded.
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[mikojh]