Analyze This! (sparkplug)

[jonsmyth]

Bike has been getting poor gas mileage. Black tailpipe. I just added new diaphragms. Should I put in new plugs, or keep these and re-evaluate in a hundred miles?

 

[ATTACH]35749[/ATTACH][ATTACH]35750[/ATTACH]

 

[RossKean]

They look good to me. Very little erosion and look like the mixture has been pretty good. No need to replace, in my opinion.

[jonsmyth]

But there is lots of black carbon in the recesses. One article said you really need to look in the nooks and crannies. I think the mixture is way too rich. I leaned out the needles and replaced 3 of the 4 diaphragms.

[5bikes]

The electrode's color is about right. The black soot around the outside near the threads is excessive. The plug maybe too hot. Is it the one the manual calls for?

The center electrode is a little hard to see in the pic but the edge looks rounded some, so I would replace them.

Good job as the doing the jet needle repositioning. The next 100-200 miles will be interesting. Listen for knock, but rarely do they.

[BradT]

Do not look bad to me. Gas mileage should be good as it looks a little hot, I would check elsewhere for the gas mileage issue. Maybe start at the wrist

 

Attached is one of the best links to read spark plugs. Think I got it from the site.

 

http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

 

Brad

[MiCarl]

The electrode color looks good, maybe a touch lean. The thread area on the other hand looks pretty coked up.

 

If you have not run this plug since you did the carb work I'd suspect the heat range is wrong (too hot keeps the electrode clean).

 

If you've run it I'd guess it was way rich and the electrodes have already scrubbed themselves. The rest of the plug will catch up.

 

On the other hand, you've got them out and new ones cost about $3/each. Give you a nice clean slate to work with...........