How to read spark plugs and how they work.
 

I just feel like alot of people get over worried about tuning if they have it right or not, When All you really need to do is read the plugs. they tell the whole story.

Here are two links that will really set you straight on how to read plugs. And how they actually work. I used to think that the differance between a hot or cold plug was the actual spark of a plug but it doesn't work that way at all. It's the size of the plug inside the combustion chamber. Comparing the plugs you'll see that colder plug have a smaller surface area. that means it's smaller so it disapates heat faster than a larger plug. It's all about how hot a plug will get within the combustion chamber you have to match the right shaped plug to your particular engine so that is stays between 500-850c to cold and it won't self clean and then it'll foul out If it gets to hot then your get preignition and detonation.

Heres two links that explain it better than I can.

http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html

http://www.ngksparkplugs.com/techinf...000&country=US

Re: How to read spark plugs and how they work.
 

I read through these last night, it has some good info, but it never mentions anything about when to pull the plugs...which is kinda the shitty part. 3rd gear pull (just like on a dyno) is what I usually do, take it to the top of the rpm and then immediately shut the car off and pull over. Pull your plugs then to read them, that way you won't have any off-boost carbon build up that may change the appearance of the plug. Now you see why it's easiest to do this on a dyno and not on the street :P

Re: How to read spark plugs and how they work.
 

Yeah I see what you meen. Back when I used to tune my dirtbike I'd get on it and make it hit where ever I felt the problem was hit the kill switch and right away pull the plug and look. If you don't like you said It mat be lean at idle or somewhere else and if you keep riding it'll burn the evidence of it being rich right off the plug.

Re: How to read spark plugs and how they work.
 

What all are you looking for when doing this?

Re: How to read spark plugs and how they work.
 

Your looking for the condition of the plug to check for signs of detonation running rich or lean things like that. In the first link from my OP it has pics off plugs in differant conditions.

Re: How to read spark plugs and how they work.
 

There is also a crude version of this in the back of haynes manuals. That is more of a stock trouble-shooting one though.

Re: How to read spark plugs and how they work.
 

good info

Re: How to read spark plugs and how they work.
 

I thought that you're asking about how to read the plugs, and I was about to post that very same link (#1) that you posted :)

Re: How to read spark plugs and how they work.
 

do you guys read the plugs to tune the ignition as well? and is it safe to do that way since it could be hard to detect detonation?