They are so cheap change em.Have to say my Dad never changed plugs in his truck until had no choice,then 2 of them did not want to come out,almost had to pull the cylinder heads off.Just saying!

 

I agree, it's cheap insurance.

My dad would never change anything on his vehicles until he absolutely had to! Even oil -- he would change the filter maybe once a year and add oil as needed, but I don't remember him ever changing the oil in the family car or pickup. Always felt sorry for whoever bought those vehicles from him...

 

i change mine when they don't work any more. i have run plugs as long as 6 years. others have lasted less than 1 week. if the bike starts the plugs stay. if it doesn't start they get replaced. it's as simple as that.

 

I replace mine according to the recomended schedule at every 10K. What the heck, they are not a big ticket item.

 

I put new plugs in my Ultra at 20K miles. The new plugs run just exactly as good as the old ones did. ............... I was sooooo happy

 

Changed first set on this bike at 21k. They still looked good so I'm still waiting to put the next set in. Have 56k on the bike now, so I've got 35k on this set so far.