which is the hotter plug

[rmrider45]

my sons rm 85 was rebuilt over the winter and i put in a ngk b9es spark plug in it . was not that easy to start for him so i put in a b10es. the higher the number , the hotter the plug ? thx

 

[IndyMX]

lower number is hotter.

 

[Patman]

Check NGK's site it has a good explination of how it all works.

 

[JGrossijr]

10 is the right NGK heat range for 02 & later RM85's. A fine wire irridium plug will be easier to start. Try BR10EIX