Hitchcocks Forum

Went to take the Electra X for a run tonight, it had been standing for about 9 days while we were away on holiday on the Bmw. Turned the gave it one kick and it started, switched it off and went indoors to get my gear on. Back out to the bike and would it start not a chance. I checked it over and found it had lost the spark so out came the tools and started to trace the fault. I cleaned connections checked the coil and tested the Ht lead for resistance and found nothing untowards. Eventually I got it to start but it was running very bad and was backfiring badly , eventually I stuck an old plug in and it ran great so I put the iridium one back in and the misfire started again so back to the old plug. I was wondering if anyone else has had trouble with iridium plugs. This one is only about 600 miles old and was bought from our hosts because I had heard that there are fakes going about and didn't want to be caught out by buying a fake

Hi Davie:
I had a BR8EIX in my Bullet for over 16000kms, only changed because it was slightly in the too- cold range. It still works well if I refit it. A good one should last a lot lot longer since they are supposed to last over 60000kms in a car engine. If you have the receipt you might get an exchange or refund.

Leon,
I have half a dozen sitting here that stopped working way too expensive to waste on Enfield

If there are 'problems' with an iridium plug its almost a certainty that the fault is not with the plug but with the engine - or choice of the 'wrong' plug for that application. My own experience of iridium plugs (from NGK and DENSO) has been first class. They may cost more than standard plugs but they are still cheap compared to petrol! I'd always use one if I had the choice.

Presto I agree with you but with the fairly primitive carbys fitted to these things and the type of fuel we are now using Iridiums are probably far too advanced for these old designs

Used both over the years, found no difference between them apart from the cost, for me "Champion" is readily available and works

I can see your point Norm but I think the improvement iridiums offer can do nothing but help on a 'basic' engine like the Bullet's. The iridium will get the best out of the ignition system, standard points type or electronic. (I think it's possible that Davie oiled the plug, by running from cold for such a short a time.)

iridium plugs cope very baldly with fouling, be it from fuel or oil.
basically they die instantly ore very quickly.

Fair point mauri - it's due to the very small centre electrode, being smaller it takes smaller amounts of debris to foul it. But if the correct heat range is used this should not happen. One problem with plugs 'failing' is that often a plug which is too hard (cold) is fitted and never reaches its proper working temperature - about 600 degrees C. In many cases Bullets are given a very easy life, short journeys at relatively low speeds. In these cases the 'recommened' heat range is often too hard (cold). A 'softer' plug will retain more heat and clean itself as it is intended to do.

As NGK explain:
‘Carbon fouling is the most common spark plug related failure, but is not a spark plug fault. Carbon deposits are conductive, and as they accumulate along the insulator nose they reduce the insulation resistance of the spark plug. As electricity always takes the path of least resistance a misfire may occur if a significant amount of carbon deposits accumulate. A spark will not form as electricity can track along the conductive carbon deposits to the metal shell rather than forming a spark across the electrode gap which has a very high resistance. The optimal operating temperature range for a spark plug is areound 500-600°C, at this temperature the spark plug is able to self clean, carbon deposits will burn off. However, if too cold (hard) a spark plug is used and this temperature is not achieved carbon fouling will occur. This is the most common reason for carbon fouling.’

Presto, I know what you are saying is correct but all the ones I have here have no sign of any carbon deposit but what must be causing the failures is something in the fuel that allows tracking inside the plug, it is certainly not a carbon build up and most of my failures where when sitting on 80/90 kph and after riding 150ks non stop so the plugs were up to temp.