Spark Plug Life

[Constant Mesh]

For the FJR two ignition coil system each spark plug fires once every engine revolution rather than every two engine revolutions. This would tend to halve the life of the spark plugs. Also, the FJR's engine speed is considerably higher than a car's engine speed for a given road speed.

@ 60 MPH --

FJR engine rpm is ~ 3500 (5th gear)

Car engine rpm is ~ 2400

Firing Rate of each FJR Plug is ~ 3500 per minute

Firing Rate of each Car Plug is ~ 1200 per minute

From the firing rate an FJR plug may have approximately 1/3 the lifespan of a car engine plug.

 

[Bike Effects]

For the FJR two ignition coil system each spark plug fires once every engine revolution rather than every two engine revolutions. This would tend to halve the life of the spark plugs. Also, the FJR's engine speed is considerably higher than a car's engine speed for a given road speed.
@ 60 MPH --

FJR engine rpm is ~ 3500 (5th gear)

Car engine rpm is ~ 2400

Firing Rate of each FJR Plug is ~ 3500 per minute

Firing Rate of each Car Plug is ~ 1200 per minute

From the firing rate an FJR plug may have approximately 1/3 the lifespan of a car engine plug.

I thought all bikes worked this way, not just the FJR.

 

[FJRottie]

Uh Oh...... :assasin:

Ok guys, no hitting below the belt, no eye gouging, and no fish hooking.

Are you ready in the red corner.....are you ready in the blue corner.....lets get it on !!

 

[Constant Mesh]

The more recent R1 and R6 engines have individual coils mounted atop each plug. For a given rpm the firing rate for these plugs would be half that of the FJR's plugs.

 

[jestal]

deleted

 

[Toynut]

I would think that the major erosion of the center electrode would occur on the compression/power stroke, rather than on the exhaust stroke. Not as much heat and pressure going on in the combustion chamber, and the spark doesn't have to work as hard to jump the gap. I would consider that half the life of a once-firing ignition system plug to be pessimistic.

 

[jestal]

delete

 

[fjrchooser]

I would guess the primary life limiting factor on a spark plug running in an unleaded environment to be the repeated heat cycling from the combustion process. Wear from the electrical arcing alone would be insignificant by comparison.

 

[jestal]

delete

 

[Toynut]

Hey Jestal,

Do you work at the Milford proving grounds or at GM ?

Just curious, we may have somewhat simular backgrounds.

Al

BTW, I think we rode by each other one day this summer, My buddy was riding my yellow DRZ400s at the time.... near White Lake or Holly area.