Resistor vs. Non-Resistor Plugs

[hotajax]

Are they interchangeable? Not sure why you can't use a non resistor when the manual calls for resistor plugs.
Wouldn't you get better combustion with non-resistor plugs? Thanks.

 

[huskihl]

Combustion is the same. Resistor plugs are designed to stop radio wave interference

 

[EFSM]

A healthy coil shouldn't know the difference. On Echo products the parts lookup specifies resistor plugs for Canada (I suppose due to radio interference laws). However, I've seen certain coils on Husqvarna trimmers that will not fire a non-resistor coil properly (they call for resistor). Also I've seen some coils on Echo trimmers that don't properly fire a resistor plug (non-resistor is stock on the 225 model).

 

[ray benson]

Are they interchangeable? Not sure why you can't use a non resistor when the manual calls for resistor plugs.
Wouldn't you get better combustion with non-resistor plugs? Thanks.

I was told by a Makita service center head mechanic that the Makita cutoff saws use a resistor plug. Using a non- resistor plug burns up the electronic ignition. He showed me 7 saws from a large contractor that all had bad ignitions. All caused by the well intentioned contractors mechanic putting in non-resistor plugs. He said if it calls for a resistor plug then use only a resistor plug.

 

[Gullet]

Combustion is the same. Resistor plugs are designed to stop radio wave interference

^^^ BINGO!

 

[EFSM]

I was told by a Makita service center head mechanic that the Makita cutoff saws use a resistor plug. Using a non- resistor plug burns up the electronic ignition. He showed me 7 saws from a large contractor that all had bad ignitions. All caused by the well intentioned contractors mechanic putting in non-resistor plugs. He said if it calls for a resistor plug then use only a resistor plug.

That's interesting. I don't have a lot of experience with Makita/Dolmar products. It would be interesting to dissect those coils and figure out what went wrong. I have seen a Husqvarna coil destroyed by not running a resistor plug. Other than that I've seen no problems. It's not worth taking a chance on a wrong plug though. I'd rather go with an incorrect heat range than non-resistor, if it calls for resistor, and I'm in a crunch.

 

[Bjorn]

I only run resitor plug on newer saws, that has auto tune or m- tronic. Older gets non resistor plug.

 

[Spike60]

Should use resistor plugs on all saws with speed limited coils. (the blue ones). Also the gray coil on the 576AT. And of course all the new AT saws, as Bjorn said above.