Green spark plug

[AHPP]

Never seen a green plug before. What does it mean?

Plug has just had a heavy ish couple of weeks in a 661. Pump petrol and Stihl Ultra, mixed a tiny bit rich, very fresh.

 

 

[AHPP]

Also just noticed, a quite pronounced black/tan border. 
 

 

[openspaceman]

Nor me but I'd say that was running weak

[GarethM]

Is that a name brand spark plug, as I presume it's leeching out the copper from the electrode ?.

[AHPP]

1 hour ago, openspaceman said:

Nor me but I'd say that was running weak

Do you mean lean? As in too much air to the fuel.

[AHPP]

56 minutes ago, GarethM said:

Is that a name brand spark plug, as I presume it's leeching out the copper from the electrode ?.

NGK

[openspaceman]

2 hours ago, AHPP said:

Do you mean lean? As in too much air to the fuel.

Yes it looks like it has run over hot and that is normally due to an excess of air to fuel.

[AHPP]

37 minutes ago, openspaceman said:

Yes it looks like it has run over hot and that is normally due to an excess of air to fuel.

I'll adjust the ECU with a screwdriver.

[AHPP]

The green has got to be copper. A mate suggested it might be added to fuel instead of lead as an antiknock additive. Can't find anything to support that but apparently there's a bit of copper in petrol anyway.

[GarethM]

 

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When it comes to spark plugs, the section most people are aware of...

Edited September 23, 2023 by GarethM