Plug issues

[OverTheHill]

Hi, sorry, by plug shorting out i just mean't oiled up which shorts the spark to earth. Tracks down the side of the sooty oily bit on the insulator & earths out on the steel base of the plug. [think that sounds right!!] run out of constructive ideas though sorry. Think if it was mine i'd give it a good hard ride around a fast paddock for a while then check the plug straight away, if looks good then ride quietly for sometime & check it again, if looks oily again, well, not sure without viewing it sorry. Maybe someone else can offer some ideas. Tis a pain i know when things like this happen. Goodluck. ps, i could suggest running a much hotter plug--but won't say that out loud incase you melt a piston but does looks far away from that happening as it is. 2strokes aye!!. One thing i'm afraid to ask but have seen the mistake made where [not saying you] person thought 50/1 mean't 50mls per liter rather than 1000 divided by 50=20mls per liter. Catch ya later.

[evo550]

You have said that all the ignition system has been replaced? Why?

Nah, I said the ignition was brand free, meaning I couldn't find who made it....lozza was mentioning NGK cap codes, I just went and had a look to see if the ignition system was NGK or something else. Frame has not been painted, wouldn't any earth problems be evident from the start, not after an hour or so?

Hi, sorry, by plug shorting out i just mean't oiled up which shorts the spark to earth. Tracks down the side of the sooty oily bit on the insulator & earths out on the steel base of the plug. [think that sounds right!!] run out of constructive ideas though sorry.

That's pretty much what I'm thinking is the problem, but what I can't understand is why isn't it happening to the two other bikes that are jetted much richer, and run the same fuel and plugs
I would have thought that if a bike can destroy a plug in an hour, it would be a blubbering, smokey mess, which isn't the case.

[Montynut]

A bad earth system will cause a weak spark due to the high resistance in the ignition circuit. With a nice perfectly clean new plug everything is fine but the spark is weak causing poor combustion and resulting in fouling of the plug. This then appears like an oiling up problem. With the weak spark the plug is very easily fouled and the poor combustion causes carbon deposits more than normal.

The HT (spark plug) circuit in basic terms starts at the HT coil lead through the plug cap, then the plug resistor, then across the plug gap to the earth electrode, through the cylinder head and engine cases back to the frame via the engine mounts and finally from the frame back to the HT coil. A bad connection anywhere will weaken the spark because it restricts current flow.

[Lozza]

Could check the air gap the spark can jump.

[Montynut]

Yep remove the plugs earth electrode and the spark should easily jump that gap. CDIs will jump much much further.

Also been caught before and it sounds a bit silly. With the fuel tank off (carbie full of fuel) test the ignition system in total darkness. Look for any errant sparks from plug leads, plug caps, coil mounts, engine mounts etc.

[OverTheHill]

one more [one more thing]--don't throw the oiled up plugs out, [if fairly new], they are still ok & just need a clean. If you get the oiling up thing sorted out the plugs will stay clean [tan colour] & be good for a very long time. In desperation [at home] i get my plugs clean enough by sitting them on an old house brick & heating the plug [at the oiled end] with my little lpg burner thungy [use it to solder cable nipples on], or i suppose hold plug with pliers vertically over the tip of any clean flame for a while to dry out & burn off the oil. Don't do what i did once with the oxy/accetylene & got a bit carried away [think it was a resistor plug--R type] & got it so hot it went off like a rifle shot & blew the top end [where cap fits on] out of the plug. Anyway--that's my 10 cent's worth.
ps ,A mate said recently he cleans his plugs with a water blaster--tried it but without much luck, maybe if you degreased the oiled bit then blasted with the jet nozzle it might give it another life once you have the motor running clean.

[Mike52]

Pics of plug,

EVO if you were to put THAT plug in now would the bike run ?

[evo550]

Pics of plug,

EVO if you were to put THAT plug in now would the bike run ?

Nope, it's been out of the bike for about 2 weeks, but still no spark.
Although I might try OTH's tip and try and clean the deposits off the insulator.

[pancho]

 Buy a can of carby cleaner. That will clean the plug [and anything else thats dirty.]  It's good gear.
 All sounds like weak spark to me.
 Next try when it stops, leave the plug in there, but don't try to start it for as long as it takes to change the plug, or a bit longer, then try to start it again with the  oily plug still left there. If it starts, it means the spark is weak and the spark is oily caused by missfire.
 Check the way the low tension leads go onto the coil, if they are wrong way around the spark will be about 25% weaker.
  Dont give up!
cheers pancho.

[Mike52]

Pics of plug,

EVO if you were to put THAT plug in now would the bike run ?

Nope, it's been out of the bike for about 2 weeks, but still no spark.
Although I might try OTH's tip and try and clean the deposits off the insulator.

Just asking because I once bought a nice little 86/125 KTM from the bike shop but it was too cheap.
After about 1/2hr it would stop running.
Let it cool down and it would start , run for 1/2 and stop again.
The previous owner had sold it cheap out of frustration.
He had also zip tied the kill switch wire to the top radiator hose.
Snipped the zip tie and found a nice short  , ran great after I fixed that one.

If that plug will not spark but another one will then the problem is the plug , maybe try another brand , non resistor, different heat range ?
I have seen boxes of  Champion resistor plugs die because of moisture in the powder that they used as a resistor , back when they first came out.

[OverTheHill]

A little hard to tell from the last pics but looks like a good quality plug [i forget what you call them] small electrode type plug & was told these need [maybe in theory] less voltage to fire them. That said, i still think looking at earlier pics that it's an oiling problem causing a lack of spark when the oil get's baked onto the insulator. Cheers for now.

[evo550]

OK so I went and got some carb cleaner and gave the tips a soak for about an hour....and it bought some back to life , but something funny is happening, when it sparks some are jumping the gap and some seem to just roll around the base of the electrode, sort of where the electrode leaves the insulator, most strange I got my son to do some gopro footage, and will try and upload later......Gettin' there 

[JohnnyO]

Sounds a like a weak lazy spark due to a buggered stator..

[evo550]

Click on pic for link.
As you watch the video, you can see the spark jumping all round the place, not just across the gap.

[Lozza]

I would get a crap old ES plug and file the centre and J strap as square as possible. Leave the kick start alone and spin the engine over with a drill on the flywheel nut Then film that
Looks like the polarity could be wrong but need a better/closer look.