OK, I have a quandry regarding some tuning terminology. When I was quite young and learning about carburetion I was taught the term and use of the phrase “Plug Chop”.
It seems to have different meaning to different people.

What does the term “Plug Chop” mean to you??

Plug chop for me means when im trying to see if im ok with my main jet . By checking my spark plug condition after i kill the engine in high revs .

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Stamatis, Bingo, right on the money, that’s a plug chop right there. Exactly what I was taught a very long time ago by some very smart guys.

Here’s why I asked what I thought was a stupid question in the first place.

The other day a guy came into my shop, told me that he had pounded out some practice laps in very cool conditions. Then he asked me if I would look at his spark plug and tell him what I thought.

It went like this, he hands me the plug and it's had the threaded portion cut off.

I looked at it and the conversation went like this:

Me: WTF did you do to this plug?
Guy: Haven’t you ever head of a plug chop?
Me: Silent and dumbfounded.
Guy: Well what do you think
Me: I think you destroyed a perfectly good spark plug!
Guy: You don’t know what your’e talking about.

After some time I thought maybe this isn’t the only guy that believes that. So I googled the term “Plug Chop”.

Tons of the responses involved, cutting up the plug including step by step instructions with pictures and videos.
Back to being silent and dumbfounded.


We are literal creatures. Plug-chop sounds like exactly what he did. That being said, one would pause to consider wether a plug that has been sawed in half would actually work.

I can’t think of any howlers off the top of my head, but I’ll bet I’ve pulled some derp moves in my time.

I guess in a ideal world, a good plug chop would be both steps. Shut down on full throttle and cut he threads off to reveal the fuel ring at the base of the insulator.

But yeah, to me it was always the process of shutting the engine down to get a good reading to being with.

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Can’t tell if this is a classic Greg Wright joke, or if our species is in cognitive decline :joy:

That said, I’m already dumb enough to buy the $50 spark plugs, so why not go the distance and “chop” them up to get a good look at the insides :man_shrugging:

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I wish I was joking but this is real. Think about this, in the last 4-5 months I’ve had to tell more than one adult male how to just change a spark plug.
It only got worse when I googled “Plug Chop” and found many adhering to this theory, as I said complete with step by step instructions including pictures and videos.

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Things sure have changed, haven’t they?

If after every tuning you need to do a “plug chop” it will get very expensive :frowning: Google says to do it to see if you have tuned it right and you cut it open to see id you have done it right… Idk really know this never heard of it acually :slight_smile:

@KartingIsLife is correct, although we all refer to it as shutting down and reading, in reality the term comes from the actual step of sawing off the threaded portion to expose the insulator and read the ring at the base, there is a specific color and depth you are looking for, much more reliable than reading the surface.

That is a technique that was commonly used in the past, especially in non kart applications. Even back in the days when EGT and lambdas were not common, in a kart you’d still have access to better indicators (read piston ceiling, exhaust flange, etc). In other applications like multi-cylinder engines in motorcycles, quads, snowmobiles etc where access to engine vitals is difficult or time consuming, cutting up a cheap spark plug (that you’d buy new just for this specific test) is a quick and reliable way to confirm jetting. Not really meant for today’s $50 mini plugs :money_with_wings: