Hotter or Colder Spark Plug

Can anyone tell me which way the numbers go on NGK spark plugs? I have a B6HS, and I want a hotter one. So is a 7 hotter? or is it a 5?

Thanks guys.


Re: Hotter or Colder Spark Plug

5 is hotter. seven is colder, eight is even colder, and nine, well you get it.

Re: Hotter or Colder Spark Plug

Jason Luther /

4 is an eternal flame

Re: Hotter or Colder Spark Plug

Thanks alot guys!

Okay the real problem behind the question, is that I am not sure if I can locate a size 56 jet for an old 12mm Bing all that soon. At least that's where I'm guessing I should be. _Someday I will have a quiver of jets._ I am running rich, and I have a 58 in there now. I was hoping a hotter plug would get me by until I at least get a smaller jet. I saw them at Rinky Toys, but I'd sure hate to put such a small order in to The Netherlands.

I emailed Matt at Motor West, and asked if he's got any. I'm thinking if I hop down two incriments, I could be running great. I see Rinke's got 57's too, but I have a feeling it won't be enough.

My spark plug chop today was dry sooty black. I'm wondering if I should even go as low as size 55.

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