# Spark Plugs



## RKDOC (Jun 20, 2006)

On a spark plug that is removed from an engine it has the marking indicating it is a resistor type plug. Will it hurt to replace with a non resistor type plug? On the other hand can a non resistor type plug be replaced with a resistor type plug? I would be keeping the heat range the same. I know on some generators, especialy those that are digital controlled you need a resistor type plug so as not to mess the governor system, But what about on regular lawn mower or chainsaw engines?

Thanks for the advice


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## pyro_maniac69 (Aug 12, 2007)

no it will not IMO, theres been arguments overs this for years

about all a resistor plug will do is stop static from being produced if your listening to the radio when you are using your equipment


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## rotti1968 (Apr 26, 2009)

well I'm going say that yes it will. Wacker who makes construction equipment has a line of units in cut off saws and their jumping jack rammer's. They are 2 stroke engined units if you use a none resistor type spark plug in them you will fry the coil. I know this for fact as I have replaced many due to this issue. Today's coils are like mini computers with circuit boards etc. They control everything from spark to timing advance to rev limiting. This also applies to makita,sachs dolmar,stihl etc. If your unit calls for a resistor type plug that's because the engineers have found that's what is required for that engine and that's what you should be using to prevent issues down the road
and yes you can use a resistor plug in replacement of a none resistor plug I just would not go the other way to protect your investment.


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## RKDOC (Jun 20, 2006)

Thanks for the info. It sounds like the best thing to do is stock resistor plugs then there shouldn't be a problem.

Thanks again


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## 30yearTech (Sep 14, 2006)

Some engines can be used with most any type of plug as long as it's the correct heat range for the engine. Some of the new electronic ignitions really need to have the correct resistor type spark plug. I just had a couple of cut off saws for repair and neither one had any spark (bad modules). They both call for a resistor type spark plug and neither had the correct plugs in them. The modules cost $145.00 each, I made sure they had the correct plug in them as I was told by the saw mfg. that use of incorrect plug could cause module failure.

I have not run across this issue on any lawn mower engines however and have used both resistor and non resistor plugs on many Briggs, Tecumseh, and Kohler engines. I generally use resistor plugs on Honda and Kawasaki, although I have not run across any issues with these engines that have been run with non resistor plugs.


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