Difference in a resistive and non-resistive spark plug?

[Rockingit]

So I'm home servicing one of my Stihl machines (2 stroke brushcutter) and my local dealer apologised that technically it should take an R (resistive) type plug but they're hard to get at the moment and a non would work fine - what's the difference??

NGK BPM6A -v- BPM6(R)A

 

[DPG]

I think it's just to suppress electrical interference. Don't they normally do it with resistors in the plug caps though? I suppose not in this case.

 

[Rockingit]

That’s what I thought, which makes it seem weird in this application. I guess a non will just produce a larger but less stable spark

 

[Marvo]

Yeah, I'm not an expert but they use a resistance of a few kiloohms to reduce the RFI. I'm not sure though if you use a non-resistive plug on an ignition coil that's designed for a resistive plug whether it might overload it and maybe premature fail. And vice versa, whether using a resistive plug on an ignition circuit that's designed for lower impedance whether it might cause a weak spark and have a negative effect on ignition efficiency and cause poor emissions.

 

[Rockingit]

I think what I’ll do is use the non R that I picked up today for as long as it takes to get the correct R one ordered in. They’re only a fiver and take seconds to swap over so it’s no big deal. Haven’t really got much choice - with all this rain/sun/rain/sun we’ve had there’s some patches of the garden verges nearly a foot high! ?

 

[telectrix]

I think what I’ll do is use the non R that I picked up today for as long as it takes to get the correct R one ordered in. They’re only a fiver and take seconds to swap over so it’s no big deal. Haven’t really got much choice - with all this rain/sun/rain/sun we’ve had there’s some patches of the garden verges nearly a foot high! ?

let them grow. bees need help these days.

 

[Rockingit]

let them grow. bees need help these days.

Indeed they do - and we’re lucky in that our ‘lawn’ is basically more of a paddock (used to be a cider orchard years ago) and one corner we let grow wild and do it’s own thing. There’s a large rabbit warren, slow worms, meadow flowers for the bees... such a huge variety of wildlife it’s wonderful. Above it is a massive old Willow that harbours the doves (we seem to have a life-mating pair that see more action than I do), have spotted a goshawk a week or so back, too. This seasons baby rabbits are quite brave still at the moment and will hop all the way over to the house and munch away only a few feet from us watching them from inside - and I know they can see us.

 

[Rockingit]

Taken just this second, looked out the window...

 

[westward10]

Looks like a cabbage.

 

[Rockingit]

Looks like a cabbage.

Might go well with one, too, after a little light roasting on the bbq