After reading a bit on Roasty Ducks thread on resistance on plugs I checked one of mine. 3.5kOhm. When hot it drops to 2.5kOhm.
I looked at this vid and it says it should be 4k to 8k Ohm. Presume then my plugs are stuffed. Now I dont by any means mind getting new plugs but am interested if this is correct.
Plug resistance.
Re: Plug resistance.
1: It depends on what plugs you run
2: NKG uses a 5k resistor
3: The resistor is for suppressing RFI
Testing resistance could tell you if there was an open, or ultra high resistance..but it does not address the condition of the center electrode ..is it eroded? is it coated by deposits?
And it could tell if there was a short between center electrode and metal body.
His suggestion to use a wire brush to clean deposits off the plug is way off base.. doing that will deposit metal on the insulator and or electrode and likely cause a misfire or outright failed plug.
It was common to use a "Spark plug cleaner" when I started out in the early 80's. Knowing what i know now about media blasting, I would never clean a plug like that....way too likely media will get trapped in the plug and release later while in use.
2: NKG uses a 5k resistor
3: The resistor is for suppressing RFI
Testing resistance could tell you if there was an open, or ultra high resistance..but it does not address the condition of the center electrode ..is it eroded? is it coated by deposits?
And it could tell if there was a short between center electrode and metal body.
His suggestion to use a wire brush to clean deposits off the plug is way off base.. doing that will deposit metal on the insulator and or electrode and likely cause a misfire or outright failed plug.
It was common to use a "Spark plug cleaner" when I started out in the early 80's. Knowing what i know now about media blasting, I would never clean a plug like that....way too likely media will get trapped in the plug and release later while in use.
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roasty_duck
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Re: Plug resistance.
as above the resistance filters rfi, which those older ones of you will know used to be a right nightmare back in the day when they didn't have any and used to mess up tv' s and radios as you rode past.
i did try cleaning my plug cap with a wire brush in a dremel, it improved the resistance a little but still reading well over 18k ohms.
bike still run.
fitted a 5k ohm and a 12k ohm and it seemed to run better but still surging.
i wouldn't really risk the wire brush in a plug cap for fear of metal coming off inside but i managed to get a spare set so it wasn't so bad.
inside the plug cap itll have a 5k ohm resistor but the issues lie between the screw on the lead side and the screw in cap on the plug side.
reality they aren't a massive issue if theyre a bit out.
i did try cleaning my plug cap with a wire brush in a dremel, it improved the resistance a little but still reading well over 18k ohms.
bike still run.
fitted a 5k ohm and a 12k ohm and it seemed to run better but still surging.
i wouldn't really risk the wire brush in a plug cap for fear of metal coming off inside but i managed to get a spare set so it wasn't so bad.
inside the plug cap itll have a 5k ohm resistor but the issues lie between the screw on the lead side and the screw in cap on the plug side.
reality they aren't a massive issue if theyre a bit out.