400ex Spark Plug

[FoxMxRiders]

My 400ex run good,my plug is dark gray and I use DPR8Z sparks plug

The temp around is 68F to 86F and its colder the morning and evening

I run syntethic 10w40 oil

I want to know if I change the spark plug for a DPR9Z that is for long high speed if my 400ex will run colder?Or it will change anything??

[cals400ex]

it won't really run colder. it will hold less heat in the plug itself. the heat has to go somewhere though. it will probably be a little harder to start too with the colder plug in. i would try both and see if you can tell a difference. i never really could but i ran the dpr9z after i built my bike.

[FoxMxRiders]

thanks

[400ex2072]

I run a 9z with no problem

[FoxMxRiders]

when I will change my sparks plug I will try it :macho