@charlie99 wrote:you may have one or several issues ...looking at plug 3 to start with it looks about right ...perhaps a just a tad rich ... but considering the rest there is something wrong
the rest look to be running lean to blazes ...that in itself will cook a plug very quickly ...perhaps a cooler heat range might be in order till you find the core issue ...for the mix you are presenting to the cylinders and the plug cables - coils are sorted .
Yep. I did say they were lean. I've been thinking about trying a D8EA. I tested my leads and coils early last year with a good result. Might look at that again, but leads will be replaced shortly.meanwhile sorry to say But your testing method is completely flawed .
With great respect charlie, I don't think so
if a parallel resistance is to earth it could read anything , and it looks that way to me that you've shown in the pics . please tell me that you weren't touching the earthy side as well as the central electrode ??!!
Nothing was earthed. In those photos I was not touching the SPs. Probe was clipped to the threaded top. I tested them several times and got the same result even after running the bike for a few days in between. I can assure you I am very familiar with using a DMM and testing procedures.1> you should test the thimble to central electrode WITHOUT TOUCHING THE GROUND ELECTRODE AT ALL . else parallel resistances can confuse the issue . I would expect the resistances to be in the lowish hundreds of ohms if faulty and nearly zero if ok 1.1 ohms sounds about right on a non resistive type plug.
NO WHERE IN THOSE PHOTOS DO YOU SEE ME TOUCHING THE ELECTRODE OR GROUND.
The faulty ones ARE in the "lowish hundreds of ohms".... That's where I'd expect the resistance values to be also.
As far as I can remember, all the new SPs I've measured were < 0.5 ohms2> you should be testing the central electrode to the earthy side ...I would be expecting meg ohms to hundreds of thousands of ohms resistance but obviously it has baked carbon deep down in there ..away from the tip who knows what it is really.
Correct. But any breakdown of the ceramic insulation would be difficult to detect/measure with a DMM. You'd need a mega to do that. Any resistance you could measure with a DMM would be in the megohm range, as you say, but would mean the plug had already stopped working by that stage.plugs will suffer from overheating and go partially open circuit as the copper electrode melts inside the ceramic from the extreme temps of a lean plug .
yes your right you cannot expect to see the real resistances under compression load ...without a high voltage source
a multi meter is not the right way to go in this case ...it can prove there is a short or open circuit at low voltage ....but that's it ...at 30,000 volts it means bugger all
Its simply a test to determine the integrity of the SP electrode which I think is quite valid, in the same way you measure the resistance in a lead or coil using a DMMpoint in hand, remember the rd 250 and 350 yamahas ...to flood them is quite easy ....to measure that flood across the plugs was impossible with a multi meter ....
put in fresh plugs and away you go, till the old ones died out or were cleaned
Yes. I remember the old RD very well but I haven't a clue about measuring the "flood accross the plugs"this is aimed at d7ea plugs ...not dr7ea which have about 5000 ohms built in with carbon before the electrode in the combustion chamber
I mentioned I was using D7EA in my OP