How often sparkplug change?

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What nettle said brings back fond memories.
In 1973 I had an automotive repair shop and we had a little spark plug cleaner sand blaster thing on the wall just for spark plugs. Spark plugs cost about 60 cents each so we cleaned them.

At that time I went to a class given by th Champion Spark Plug factory.
It was very informative. One thing that impressed me was that he said that just because it is new does not mean that it is good. He also said that if there was a problem in manufacturing that thousands of plugs might get made in just a few hours. Those plugs get sent to a warehouse and every store in a hundred miles might use the same warehouse. That meant that every part in my town could have the same bad batch. Putting in new is no guarantee and adds a risk factor. How many risk factors can you guys think of? Just food for thought.
 
I don't change plugs unless they seem to be going bad, which to me is most often identified by hard starting.

And they do go bad, I recently fixed up a Weed Eater trimmer, would not start even though you could see a spark with the plug removed. Put in a new plug and it ran like new.

I've fouled more plugs in atvs, dirtbikes, snowmobiles, and other 2 strokes than i could ever count. I always thought very highly of NGK, and still do. I did also always believe that once a plug was really oil-fouled, it seemed like something was damaged internally and it was never the same, even after being cleaned.
 
Heck, I just got an old Lombard running after who knows how many years of sitting. I never even pulled the plug to look at it lol. Dont even know what brand it is!
 
I figure pay now or pay later Murphy’s law can bite us at anytime. The sparkplug is the weakest link.

You carry extra new spark plugs right? I save my old plugs and clean them. They have plastic sealed tubes to keep clean plugs in. Your local dirtbike shop sells them. Or pvc with two end caps works, one glued one loose.
You seem to put a lot of work into a spark plug that probably doesnt need to be changed. Why not just carry an extra plug incase one craps out instead of changing them all every season? I haven't changed a plug in years. My saws run good with years old spark plugs.
 
I had a couple old paint cans of used spark plugs from chainsaws and string trimmers that were parted out and a couple cans from saw shops that changed plugs as part of a tune up. Most of those plugs were barely used, maybe a couple gallons of fuel for many of those plugs.

The bad part was the volume of plugs that were just incorrect size, type whatever. There were bad plugs as well, however the bulk were barely used, many of the good plugs are still being used now.

The only thing that became obvious was every brand can make a bad plug. The other things I learned was there are people that collect old spark plugs, or any spark plug they do not have an example of.

I will change spark plugs when they no longer work or look worn.
 
I can remember the days when spark plugs were sand blasted, electrode filed flat again, and reused. We were thrifty back in those days.
First GM dealership I worked at had a plug cleaner mounted on the wall. We would still use it time from time for local customers that believed in cleaning them and reinstalling them. I've had used it a few times myself cleaning my lawnmower plug, burnt oil real bad and fouling out the plug.

Steve Sidwell
 
Still do that today. Whats this back in those days comment :)

Yep. I just blast them clean and they’re good to go.

I also never trust that what I’m working on has the correct plug. You never know what the previous owner may have installed. If I don’t have the correct plug I try to find a Denso first but I’ll use NGK as my second choice.
 
I can remember the days when spark plugs were sand blasted, electrode filed flat again, and reused. We were thrifty back in those days.
Way back in the 60's I started work at gas station that had a sparkplug tester, it had a big thick rubber grommet on the line for the sparkplug, surely no spark can get through that, I was holding it as I pressed the button, I thought someone batted me across the shoulders with a 2x6!
 
We were playing with the Allen diagnostic scope at the dealer. We took used plugs and cleaned them, filed the electrode flat again. The machine didn’t know the difference between used or new. this was back in the 70’s.
So, you proved the point, just clean a used plug and keep using it. Now, I do not understand why you would be changing a good plug out every year? Even your machine could not tell a difference.
 
I see no reason to throw money at a new spark plug just because it has worked for specific time. If saw aint running right then yea spark plug will the first part to be replaced.
 
I'd love to go through a service department bin and dig out all them hardly used spark plugs that get replaced. I clean my spark plugs on daily used work saws at least a couple of times per year, tune gap etc. But quality sparkplugs have a very long service life, the only few I've had to replace have broken or the electrode broke off.
 
I keep one either on me or in the truck when I’m not far from the road. When the saw acts like it’s not firing, I replace it. If not, I leave it alone. There’s no point in trying to fix something that’s already running well.

I get the point of preventative maintenance, but I’ve never considered spark plugs part of a PM. I’ve always seen them as a consumable item to replaced as needed.
 
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