Spark Plugs - Cold / hot?/ what the ???

[CBXboy]

hey group,



so... my stock plug for cbx250 is DPR8Z , but I could only find a DPR9Z at the store.



Drove the bike yesterday, it seemed fine with it.



I understand that the higher the number the colder the plug?? What exactly does this mean? Am I at risk of damaging the engine?



thanks again,



CBXboy