ngk 7 spark plug heat range

SDE · Sep 21, 2018

My ATV has always been a cold blooded starting machine, for the first start of the day. I bought a new NGK plug and I replaced the old Champion plug. The old plug was an 8 and the new a 7. WOW! It starts great now. The old plug did not look bad. So is it a difference in the heat range that makes the difference? Or is an NGK 7 heat range the same as a Champion 8 heat range?
TY
SDE

rustyfarmall · Sep 21, 2018

Can't answer your question, but I have had some Champions that looked very good, and wouldn't fire a lick.

CBBC · Sep 21, 2018

I use NGK 5 and 6 in Hondas from 5 hp-24 ho.

The twin Kawasaki in the gators will run on 5 but mush better on 2 .... which is what it the numbers crossed into. It seemed pretty hot but works much better.

I try to get NGK in everything except my old Johnson 9.9 outboard.
Grant

Crazy Horse · Sep 21, 2018

Not sure but doesn't the heat range have something to do with an engine once it is running? Oil consumption and its effect on plug life and performance comes to mind. I don't think I've ever heard of it being a factor in starting up, but correct me if I'm wrong on that.

Jeff NWOH · Sep 21, 2018

I'd venture to guess that getting rid of the Champion plug is what solved your starting issue. I've never had much luck with Champion. NGK is my plug of choice.

jeffcat · Sep 21, 2018

You can do a little research on the NGK site. I think something to the effect their range is reverse. Lower is hotter if correct. Anyhow. ...do yourself a big favor. Did this machine take a BPR6ES plug? Larger engines take that plug and 5hp engines take the BPR5ES Plugs. Now a lot of my stuff also has NGK plugs but here is what you want to do. Check the NGK site if you are not sure and then go on Ebay. Buy a box of Iridium sparkplugs. They are absolutely fantastic!!!. My engines start faster than I can let go of the key. My engines LOVE them. Bo5h of Briggs 22hp twin-V engines have them and several Kohler and Kawasaki engines too.

4play · Sep 21, 2018

Heat range should have zero effect on cold starts, idle speed and low load conditions. The heat range is determined by how long it takes a spark plug to transfer heat to the cylinder head. There is not a universal measurement, heat range from one manufacturer can be totally different from another.

Steve@Advance · Sep 21, 2018

Time will tell...

A plug will always work best when it's new. If it's gaped properly, the engine is healthy, the proper heat range, the mixture is right, and getting good spark, it will last a long time.

But even under optimal conditions exposure to combustion will leave an ever so slight coating of carbon on the insulator. The carbon is conductive, so some of the spark charge will bleed off through the carbon. A too cold plug will accumulate more carbon, eventually to the point it will not fire at all.

If the original plug was too cold, then it could have been having bleed off problems, or if it was worn to the point the gap was too wide for the spark to reliably jump, a new plug will fix it.

But if the problem returns after a few miles, there could be a problem with weak spark at low RPM, or a too lean mixture.

If that has a carburetor, it is probably a slide type carb with a tapered needle under the slide. There is a snap ring with adjustment groves to set the position of the needle. Try raising the needle one groove. It's easy, and returnable to the original if it doesn't work, but I think you will like the results.

mj · Sep 21, 2018

(quoted from post at 07:58:36 09/21/18) My ATV has always been a cold blooded starting machine, for the first start of the day. I bought a new NGK plug and I replaced the old Champion plug. The old plug was an 8 and the new a 7. WOW! It starts great now. The old plug did not look bad. So is it a difference in the heat range that makes the difference? Or is an NGK 7 heat range the same as a Champion 8 heat range?
TY
SDE

Try a 'non-resistor' plug.

2x4 · Sep 22, 2018

When I had a Stihl dealership I took the Chump-ions out of the new saws & put in Bosch. That ended new saws that wouldn't start.

ngk 7 spark plug heat range

SDE

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rustyfarmall

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CBBC

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Crazy Horse

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Jeff NWOH

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jeffcat

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4play

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Steve@Advance

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mj

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2x4

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