Powerdynamo, spark plug failures, bad plugs on the market

Powerdynamo brings new ignition & light
to your vintage motorcycle



Technical Help



Quite often customers report:
  • after a few kilometers (miles) engine sputters, dies and does not start again
  • engine starts when cold, but dies when hot and starts only again when again cold

    In hot weather periods we get such reports nearly every other day. At the end of the day, in the majority of cases it turned out the spark plug was the culprit.
The market is presently swamped by very bad spark plugs made in Far East. Price ex China between 11 and 25 US Cent (see here). We had experienced already in 2009 massive spark plug problems, now the problem is here again.


we have again and again customers who, faced with ignition failure on hot engines, are dead sure that the reason is a faulty powerdynamo ignition coil.

Many start to mess around with instruments to check the coil. Some even introduce battery voltage to "amplify" spark - with the effect of killing the thing right away!

Why this is not only not bringing any results, but is outrightly dangerous for the coil you can see in the picture here. The unit is full of electronics!

Checking resistance of the secondary winding (that is HT exit against ground) is the only thing you can do. 

We have next to no failures of those coils (unless they have been subjected to wrong installation). In virtually no case has the coil finally found to be the culprit.

It is invariably nearly always the spark plug (even if brand new) and/or spark plug (resistor) cap or the carb, the petrol(gas) valve or even the petrol(gas) tank vent (see info here
He who has ignition problems and knows that his spark plug is not of a known make should take it out and throw it away. Known makes are e.g. Bosch, NGK, Champion, also Beru, but not AKA (which  swamps German ebay)

Please do not discard this information as irrelevant, only as you have fitted a new plug. Those plugs are bad from start.

Powerdynamo spark with a quality plug Powerdynamo spark with a (new) bad plug made in China
The bad plug diffuses the spark. The whole electrode is in rather white flames whereas the good spark is see-through blue.
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