Topic: Sparkplug life span

[70CB750]

I did 3000 miles tune up yesterday, plugs seems ok, they last longer than 3K, right?  I know car plugs are 10s of thousands easily.

How do you know spark plug is gonne bad? Cold starts are hard? 

[bollingball]

I look for how much wear there is on the center electrode and ground strap or if has oil fouled. If the bike is tuned well maybe go 6000. As long as it fires well and still has meat on the bone let it rip.

Ken

[Duanob]

I have less than 3000 on mine and I'm already noticing harder starts on colder mornings. They are cheap I will replace them.

[lucky]

I did 3000 miles tune up yesterday, plugs seems ok, they last longer than 3K, right?  I know car plugs are 10s of thousands easily.

How do you know spark plug is gonne bad? Cold starts are hard?

"plugs seem ok"  What does that mean???

When you are looking at spark plugs look at :
The gap.
See if the ground or electrode is degraded and rounded off.
You cannot see the compression seal, but they do make testers that check the spark WHILE the plug is under compression.

The number of miles is based on mileage and type of driving.
Freeway driving or around town etc.,.
Each engine of a car or a motorcycle will be different with the same spark plug based on cylinder head design and all other factors of the engine and electrical system and the driving habits of the owner.

And finally the weather of the area you live in. Hot or cold climate.


BTW... Engines having difficult cold starts does not mean it is the spark plugs or electrical system. Cold climates are harder on electrical systems  to start.
But once it is running then heat is the enemy. For instance electrons flow easily in desert heat, but once the engine is running in 100º F heat then that has limits too.

Even cooling systems can effect plug life.

For instance on a regular 4 cylinder engine that is not transverse mounted #4 plug ( the one in the back) is usually running richer.
So with plug changes you might want to swap those plugs around.
Some electronic testers now can anaylize the quality of the spark and display it on a screen.

[70CB750]

I did 3000 miles tune up yesterday, plugs seems ok, they last longer than 3K, right?  I know car plugs are 10s of thousands easily.

How do you know spark plug is gonne bad? Cold starts are hard?

"plugs seem ok"  What does that mean???

That means that the plug looks ok.

[TwoTired]

I did 3000 miles tune up yesterday, plugs seems ok, they last longer than 3K, right?  I know car plugs are 10s of thousands easily.

How do you know spark plug is gonne bad? Cold starts are hard?

12,000 miles is about it with these old ignition systems.

Essentially you look at the electrodes.  As they wear, the edges get rounded, and this makes them more difficult to spark with the relatively low voltages the old systems provide.
One of the reasons ignition systems evolved is that old spark plug can fire like new ones if much higher energy, higher voltage is applied to the electrodes.

Old spark plugs can be reconditioned to fire as nearly new ones by filing the electrodes flat and putting the square sharp edges back on them.  Then re-gap to  about .025".  I usually bend up the ground strap for a thin flat file to get in there.  File the center and the ground strap for flat square edges.  Then bend the ground strap back for proper gap.  They fire like new ones.  If you are using resistor plugs, measure the resistor for about 5K Ω.  If they have opened, the resistor has gone bad and the plug needs replacement.  I prefer to replace them all as a set, and put one or two reconditioned ones in the tool kit.  Of course, cracked or damaged porcelain signifies a replacement need.

Cheers,

[70CB750]

Thank you, TT.