Spark plug mileage

Out of curiosity, roughly how many miles do you's get from your plugs before replacing them? I have a habit of putting new plugs in every spring. However, I'm looking at my plugs from last year, that I saved and cleaned. These things look like they have a LOT of life in them still. I think that I'm wasting plugs by tossing them after only 5-7000 km's.

i around 8000 miles on each set in my kz, but I could probably just clean and reinstall. I've got 100k miles on the plugs in my pickup truck, but that could just be a fluke.

Over the past few years I have put nearly 20K miles on my original KZ900 carb test bike and have the same plugs in... I clean them every now and then with a spark plug sand blast gizmo but they still look fine.

While I didn't think much of my auto mechanics teacher at Vo-Tech (way back in high school) he taught us that spark plugs DON'T wear out! If the engine is not tuned right or has a problem causing the plugs to run to hot or to cold, or if the engine is running to rich or to lean, then plugs can be damaged and need to be replaced. As long as everything is in the right parameters tho, spark plugs should never need to be replaced.

I replace mine every fall right before winter. Do I need to? Probably not, they look ok when I pull them out. But it makes me feel more confident in the vehicle and no more than plugs cost why not?

Plus I always have spare plugs lying around.:woohoo:

I felt a little foolish with this post actually, but, it was just one of those little things that you catch here and there. Looks like I'll be using my old plugs for now on until they wear out. Clean them, regap them, a little anti-seize on the threads, and rock n' roll.

I'd go about 12000 miles on a set of plugs before changing them... the plugs will last about 20,000 miles or more but if you change them somewhere about half their life expectancy you'll always have the maximum spark out of them.

Now if you're running rich or burning oil you'll have to either change them more frequently or clean them a lot more often and still need to change them sooner.

The exception to the rule is platinum plugs... they will out last ANY conventional plug but their spark power is considerably less due to platinum's natural resistance.

Copper plugs offer the least resistance and the most spark power but at the cost of having to replace the plugs way sooner than normal. Copper plugs are best used for racing... otherwise, just leave them alone.

Now we have irridium plugs that offer almost the same spark power of copper plugs with the same life span as platinum but the cost is out of most people's bugets still, making it cheapest to buy conventional plugs and changing them at or before 12,000 miles.

Personally I'd pay for the irridiums but for now my conventional NGK's are doing just fine so I'll do the switch when these wear out.

Has anyone out there in KZ land tried the Splitfire plugs? If so, were there any differences?

SplitFire Plugs are the biggest joke, Spark will only jump to the closest electrode. so as we learned in electrical class, Path of least resistance. so as the gap of the plug increases the splitfire will find the path of least resistance and jump to the closest electrode. But will not I again stress Will not jump to both electrode ends at the same time. there for your plug would in practice last longer but at the cost of more cost per plug.

The split gives the spark more places to go, as they like sharp points to jump to. If you look at the electrode on your older plugs, you'll see that the cylindrical electrode starts to round off on the sharp edges. This is the spark plug wear. This will wear more under the curved grounded back part to the tip, rather than the front. The spark will still occur, but the ideal spark is to get it to ignite the fuel. As long as you have a good spark, combustion will occur, and you'll be fine. The more that electrode is rounded off, the more spark energy is required to make that jump(this is according to NGK's Website ). NGK Iriduim I am running Iriduims in my GPz550 by choice, and I only paid about $10.00 a plug. I shouldn't have to replace them for a very long time. There's good information on that site about reading your plug, and choosing the right heat range, as not all plug manufacturers have the same heat range scale.

Post edited by: CoreyClough, at: 2005/10/24 10:36

This last set I've had in for almost 10,000 miles (since last October) although I do change the plugs out on all my bikes every spring regardless. I use NGK BP7ES plugs, 8MM sheilded wires, and Dyna 3 Ohm coils.

The set that I was talking about were from 2 years ago. The set that's in there now have even more wear in them than those. Looks like I'll stay with the "new plugs in spring system" and keep the better cleaned plugs in a plastic bag under the seat. When regaped and cleaned, the old plugs can still be usefull for plug chop referencing I suppose.