Spark Plug Replacement: How Often For A Mower ?

Hello:
Just bought a new Toro Lawnmower (self propelled) Have about 1/4 acre of grass, which I expect I'll be mowing about once a week in July and Aug.
Was wondering:
How often should I consider replacing the spark plug ? Once per season, or... ?
Wouldn't really want to wait until there is some sign that it needs it; would rather do it on a preventative maintence concept, before it really needs it. What's reasonable ?
Also, the same question for a 2-cycle engine weed wacker. How often do you think for this gadget ?
Thanks, Bob
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On Mon, 20 Jun 2005 07:08:04 -0400, Robert11 wrote:

Probably never. I have a 12 year old generic push mower with a 3.5 HP Briggs and Stratton engine, and have NEVER replaced the plug. It runs as good as the day I bought it, and has been used regularly.
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I generally only replace mine when I notice it getting harder to start. I have a Honda Harmony and it usually starts on the first pull, and if not, the second.
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Maybe every 10 years or so. The one time I did replace the plug, it was no better starting as the engine was just worn out. Bought a new mower and it is on the same plug at about year 7. Starts on one pul. Lov e that John Deere

Maybe every 5 or 6 years, but if you clean it, probably 10/
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wrote:

My 9 year old Sears Craftsman mower is on its original plug. Starts first pull every time, except the first use of the season when it may take three pulls to ignite the stale gas that's been sitting in the tank all winter :-).
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You're likely to get a lot of responses like Dan gave you, and they're occasionally true, but ... they also operate at less than optimum power and efficiency.
Per season is a good, "safe" interval which should keep your machine running reasonably well. How much or how fast plugs become damaged depend on a a lot of things such as design, how hard it's asked to work, ambient temperatures, speeds used, carburation, storage methods, and so on. They're not expensive and if you're willing, you won't be sorry for doing it once a year.
Assuming a 4 cycle engine: The manuals usually recommend each season too. Well, it can't hurt, that's for sure, and if a plug goes resistive or starts to crack, you're not likely to ever notice it that way. I used to do it every other season, on the even numbered years since we have a pretty short season here in upstate NY. I made that decision one day when I was in Florida and came across the exact same mower I had, and it still only recommended yearly changes <g>. I was younger in those days and had less time, so I switched to every two years. Nowadays I go three years or so, but each season I pull the plugs and do a visual for wear, clean and regap them. Once in awhile after particularly harsh cutting season I'll see a little electrode wear, and that plug gets replaced. Usually the gaps are off a touch, but never much, so that's just a touchup. It's pretty easy to learn to do if you are at all mechanically inclined or interested. It's always a good idea to also check that it idles and runs at full speed OK, and goes from idle to max and max back to idle smoothly. If not, there are some easy adjustments on the carb that can be made too. The manuals are usually pretty good about explaining how to do that as the amount of adjustments possible vary, especially on the newer engines. Some even have no adjustments possible. The most important thing is to keep the oil level right and change it on schedules. I mow about an acre all summer, and the full 5 acres twice a summer, depending on what's going on that summer. I change the oil about midseason and do a good lube and oil change, sharpen the blades, check the fuel filter, etc. prior to storing the equipment for the winter. That way it's about ready to go next season. I also keep a set of plugs handy for "just in case" now.
As for weed eaters, it's probably best to change the plug each season; I do, anyway. They're usually 2 cycle engines and those seem to be harder on plugs than the 4 cycles, assuming you keep the gas/oil mix right.
The manual/s won't lead you wrong. I presently have a 1979 rotary push mower, a 1985 weed eater, a 1990 and a 2002 lawn tractor, , 24 and 48 inch cut, 10 and 20 HP respectively. Now if I could just figure out how to get the bodies of the lawn tractors to quit rotthing away, I'd be all set. The engines last fine, but keeping those damned decks from trashing themselves seems to be an impossibility. I sold the engine from my old 1983 mower for $100 finally, when the deck was too shot to hold the bearings/pulleys for the belts any longer. I used the deck pulleys to make a blade-balancing stand for sharpening blades, the wheels for a homemade wagon, and the ammeter for my battery charger. I"ve still got the transaxle, but I think a kid down the road wants that this summer. The blades are hung up as souvenirs and the rest of the body's sitting out in a tree line now, finishing up rusting. Yes, we live in the country; very country in fact.
HTH,
PopS

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You're supposed to change them?
Best regards, Bob
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About as often as you change engines, in fact. With aluminum or magnesium (chainsaw) threads, you're probably as likely to do harm as good by obsessively changing plugs.
I'd: 1. Keep the fuel fresh 2. Change the oil regularly 3. Exercise the engines
HTH, J
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I simply clean the spark plug in my mower each Spring. Must be 8 or 9 years now with the same plug and it fires up first time every time. Des

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