yamaha xs650 spark plugs?

[jim1075pierce]

i need some help on heat range is a ngk BP7ES colder or hoter then a BP9ES i think the 9 is a colder plug but i dont know for sure can any one help i thank you all for help pop pop.

 

[guardrailjim]

As the numbers go up, the heat range gets colder.
As they go down - hotter.

Up to heaven - cool
Down to hel - hot

 

[Dylan]

yeah the br9 is a colder plug then the7. I use a BR9 on my yz80 and yz125.