Help...killing plugs

[daveh]

Anyone help with this...

I take the scooter out for say a 20-30mile ride- new spark plug fitted...seems to be once I slow down / stop at traffic lights the scooter will start miss firing ..then it will die...check for a spark ..nothing...spark plug never seems to produce a spark again!?

What kills spark plugs?..overheating/ bad cooling ?...electrical system related...any ideas ?

Regards,
Dave

[Boo]

Could be low tension coil breaking down or cdi

[hendy]

I assume from what you've said that once you replace the plug everything is ok albeit temporarily.

If that is the case then it probably means your plug is fouled.

Have you tried cleaning a 'dead' plug then reusing it?

[bristolmod]

lots of fake NGK's about as well

[drunkmunkey6969]

lots of fake NGK's about as well

Yup, true.

I use NGK but only buy from an authorised UK wholesaler. I'd never risk eBay for plugs.

[dapper]

Get a Nippon Denso W24EU. Never had a problem since I changed to them. Had dodgy NGK's in the past.

[mick1]

What plug you using ? maybe try a hotter/colder plug

[daveh]

Thanks all...

Have used Nippon, Champion and NGK...the last one to fail was Champion!

The plug looks a reasonably good colour , no visible fouling ..but no spark..I will give it a going over with the wire brush. It just seems like heat is building up in the head and frying the plug...maybe need a Head temp Gauge to prove that one out. Not sure why I get that feeling exactly but is almost that the forced air cooling is reduced when slowing down/ stopping at lights and the temp is peaking ?! ...but not sure if any overheat would stop the plug from sparking for ever more ?

[drunkmunkey6969]

Is your ht cap an ngk resistor type......or a non resistor type?

[tonydevon]

also is the cap a good fit?

right cap for the type of nipple on the plug, if the caps loose or your using a screw on nipple type cap without the nipple then your creating an arc from cap to plug, this in turn makes a higher HT voltage and while its great as it makes bigger spark, it will also kill the plug

its an old trick from my out in the woods or trail riding days, foul the plug and no time or more likely as a kid no tools to get plug out, simply remove cap and sit it off so that theres air gap inside the cap, pretty much always worked. but long term it would damage the plug