how often to change spark plugs

 

The best answer is what it says in the manual but the reality is you can tell when it's ready. Pull out, inspect, brush with a wire brush, re-gap - reinstall. They can easily last double the mileage recommended or better.

 

After changing, I always place the old plugs in a protective container and keep them in the saddlebags.
(I have an Ultra.)
I know they worked before and if needed, they can be reused on the road.

 

Now everything has CDI ignition. (capacitor discharge ignition)
Where before everything had points.
In cars with CDI plugs last over 100,000 miles.
My 47 year old Triumph has points and I change the plugs every couple of years,
the Harley only if there is a problem.
I worked for Champion Spark Plug for 30 years.

 

FYI - While generally true, these cars would never come anywhere close to the 100,000 miles if they weren't using iridium spark plugs. Iridium plugs are the real key to the 100,000 mile change interval.

 

Those must be the ones made in Mexico Charley, because all Champion Spark Plugs are now made in Mexico.
Champion makes Harley Davidson spark plugs, I made billions of Harley plugs. LOL
Hey maybe the Donald will bring them back. LOL

 

Yep, I ran Champion RA8HC's for years in the bike, close to 100,000 miles. Switched to NGK iridium's after I built the motor.

 

NGK Iridiums, put them in and forget about them.

 

i change mine if they don't work anymore. if it ain't broke, don't fix it.

 

I use NGK iridium too, I saw early wear on the HD plugs so I switched and
It seemed like an improvement