plug reading

[Shade]

what would be a pro's opinion on this plug

one side of it's really clean, the other side has some buildup on it.

the engine shut off at WOT in a cut (actually the top of the plug vibrated loose and killed the saw when it came apart in a cut), so the saw stopped immediately.

 

[Shade]

here's the other side:

 

[Kneejerk Bombas]

I'd say the plug fell out, look at the oil on the threads.

Looks like another case of a plug going bad...

 

[Shade]

wire lead attachment fell off. the plug was tight.

 

[Stumper]

The print on that plug is really small but as best as I could make out it contains a treatise on "Why Sparkplugs Don't Go Bad", by Mike Maas.

That plug doesn't look like it has been in very long-maybe running a touch hot.

 

[Shade]

i've been milling with it... not too many hours, after looking at how clean the one side was, I was concerned that it may be running a tad lean, but from the looks of the other side, I don't know.

Thanks for the replies, guys.

 

[wiley_p]

if the lead was loose it would seem that would create a hotter spark due to incrrease in the gap. that would juice the plug more.

 

[Crofter]

Wiley P. is correct: an extra gap whose resistance exceeds the plugs gap requires the voltage to rise to a higher level before spark occurs. This effect was used to reduce fouling tendency on some designs ( created RF interference though)

I think the colour pattern could be caused by the fuel charge being directed in a loop pattern and impinging against the one side of the plug more than the other. The oil and additives from the fuel could be baking onto that side. Look at how the plug is indexed in the cylinder and see if it has a relationship to the charge flow in the cylinder.

Frank

 

[oakman]

that saw is running hot and lean. fatten it up or its goin bye bye. milling in the summer kills saws quick. thats why i only mill in winter.

 

[bwalker]

It appears to me that the plug has molten aluminum on it. If thats the case your in trouble.

 

[Crofter]

I only got a look at the black side plug at first. The light side looks a way too light unless it is the photo. Shouldnt be any lighter coloured than a tan colour. There sure is a discrepancy in the two sides of it tho.

Frank