used Spark plug analysis

[GAgunLAWbooklet]

I've never tried to diagnose the condition of an engine and carburetor system by looking at used spark plugs before.

These spark plugs came out of my V-twin motorcycle engine, where each cylinder has two intake ports and one exhaust port and there is one spark plug next to each intake Port, so that's 4 spark plugs for this two cylinder engine.

They were in for approximately 1600 miles of riding over 2 years' time.
The first 500 miles were done under conditions where the carburetor needed re-jetting.

The next 1100 miles came after the carburetor work was finished, and the engine ran strong with no apparent problems (other than some overheating issues which I think were related to the radiator fan and the thermostat. Both of those problems were recently fixed, only during the last maybe 300 miles of these spark plugs' use, but I always shut the bike down when it showed signs of overheating.)

 

[GAgunLAWbooklet]

 

[GAgunLAWbooklet]

I did consult the Clymer's service manual which has a photo of various spark plug conditions in the troubleshooting and maintenance section.

 

[bambam]

I would check the oil level and make sure it is not overfilled. Check level per owners manual.

 

[GAgunLAWbooklet]

PS: For most of the time that these
spark plugs were in service, my preferred fuel for the bike was REC-90 non ethanol gas mixed with Marvel's Mystery Oil at the recommended concentration (I think that was half an ounce of MMO per gallon if I remember right.)

 

[moosensquirrel]

PS: For most of the time that these
spark plugs were in service, my preferred fuel for the bike was REC-90 non ethanol gas mixed with Marvel's Mystery Oil at the recommended concentration (I think that was half an ounce of MMO per gallon if I remember right.)

Please show us a photo of the bike

 

[cskiles]

I would think that the motor is running lean, especially the right bank. The carburetor could be jetted to small, if it runs right (e.g., plenty of power down low and smooth increase when opening throttle) then I would leave it as is, the plugs aren't melting at the electrode (center or ground side) so I wouldn't worry about it too much unless it is starving for fuel when you get into it.

 

[Tony2X]

Looks like old spark plugs to me.

Put new ones in, make a 1/4 mile pass and then check.

 

[JBWJr]

I always used this site:

How do I "read" a spark plug? - NGK Spark Plugs

Learn how to analyze your engine's overall operating condition just by looking at your spark plugs. Find this and other DIY tips on our resource page.

ngksparkplugs.com

 

[GAgunLAWbooklet]

I would check the oil level and make sure it is not overfilled. Check level per owners manual.

Ok, did that last night at your suggestion.
( it's a real pain in the *** to do correctly according to the Honda manual.)

Oil is fine. Full, as usual. Clean. No gas smell. Color of maple syrup but not as thick once the engine is warm.