br8 or br 9

[Barton]

When to dealer today to get spare spark plug, he supplied br9eg not br8eg. If I use it what is the effect, its one heat range hotter?,
Bikes previous owner ran putoline mx7 at 40:1 theres a lot of oil deposits out of the silencer as I ride trails etc so was going to try diffrent plug or go 50:1on the premix,

Whats the thoughts

 

[noobi]

On what bike?

300s are typically a 7, 200/250 an 8, and 125s a 9.

Rule of thumb, there can be exceptions.

BTW, the higher the number, the cooler the plug.
High revving motors run cooler plugs.

 

[lgr]

its one heat range cooler. NGK is lower number, hotter plug

 

[Barton]

It 09 ec250 sixdays,