How many spark plugs?

[T.Hopp]

For a 4oo EX, I know that there are spark plugs that are considered "hot" and some that are considered "cool". Does anyone know the NGK model of these and if they are cosidered a "hot or cold" plug. I'm putting together a 416 10:1 w/ a degree key after break-in and am concerned about overheating.

[JOEX]

NGK DPR8Z is standard
NGK DPR9Z is colder

[wilkin250r]

A quick lesson. A "colder" plug won't actually make the engine run cooler, it just means the electrode of the spark plug will be colder. If it's too cold, it will collect deposits and get corroded. Also, if you're trying to read your spark plug for jetting, you won't get an accurate reading if you have the wrong heat range.