Spark Plug Help

[Astro_Guy]

The fail safe way is to take one out and look at the number.
My JD X320 had one number hotter than the manual said.
Has anyone tried iridium or platinum plugs in their lawn tractors?

I have over 200 hours on the NGK Iridium plugs in my JD D140. I've been replacing the factory plugs with NGK Iridium plugs in all of my OPE for 7-8 years now. No complaints to report for the most part. I have a Honda Harmony mower with the GCV 160 engine that has several hundred hous on it, and it is hard starting when left idle for weeks. It starts after 2-3 pulls when operated every two weeks. Not sure if this is a plug problem. It had been a first pull start on the copper plug. Maybe I will go back and see if it makes a difference.

 

[Skippy722]

I have not, but I am not sure how much they would help? Just asking - no expert.

My limited understanding.

A platinum plug might last longer, but would it fire hot enough with the relatively low voltage magneto ignition than a standard copper core which has less internal resistance?

A Iridium definitely has more internal resistance. Its primary benefit beyond longevity would be that it has a cleaner spark, for fast fire under higher compression. Again - what I have been told or read

I would also be interested to know?

Almost all spark plugs use a copper core, both for its electrical characteristics as well as its thermal ones. The copper is coated in nickel to keep the copper from melting. Platinum/Iridium take that a step further and put a tiny little piece of precious metal on the top to improve durability. The fine wire plugs also require less voltage to spark.

A lot of plugs also are “resistor” type plus, like the RN14YC mentioned above. This cuts down on unwanted RF interference at the cost of some spark energy.