New bad plugs?

[roadrocket]

I wanted to test another issue with my RR, and went for at small ride. But that never came to anything, because the bike would not run properly, and fired only well on the left hand cylinder. I have just changed plugs from some called Yqyem or suchlike to Champion N4C. Could they be bad out of the box?

[Greybeard]

I have had some misfiring a few times and thought a plug might be failing; first though I tried a good full throttle burn-up and the problem went away. These bikes need to be given their head sometimes.

[muskrat]

Yes they can be dead in the box but unlikely. Clean them and swap'em over. If the problem follows the plug, solved. I have better luck with NGK's rather than Champs but others here find the opposite.
Cheers

[Butch (cb)]

I've suffered dead new plugs a few times. Makes me reluctant to swap out old ones when they are working.

[metalflake11]

NGK plugs are made in France and Japan. The French ones have no quality control measures and can definately be faulty from new. There is no doubt about this, it is a fact.
I don't know about Champion, but mine will not run well using them in any event.
Try Denso W20ES-U.

[WozzA]

I've got 5 or 6 boxes of CROOK new plugs in the shed that I have replaced after running on one cylinder.. 
Funny thing is that after the maggy was rebuilt it hasn't happened again.. 

now I've got 5 or 6 boxes of spare GOOD new plugs in the shed..   

[beezermacc]

This type of misfire is often due to poor carbon brushes which contaminate the slip ring, which is why the problem is resolved after the magneto has been rebuilt  [quote from previous post - "Funny thing is that after the maggy was rebuilt it hasn't happened again.."]
.I would recommend changing the brushes for known good quality ones and clean the slip ring. You can do this by wrapping some emery over the end of a tube, poking it through a pickup window and turning the bike over. Check the condition of the slip ring with a small mirror.

[nimrod650]

fitted new plugs ngk correct type and new points and  oil change on my 58 6t took it for a spin round the block pushed it home checked it over nothing fitted the old plugs ran like a dream

[jachenbach]

I've had new plugs bad out of the box twice in my life. Once in a Karmann Ghia and the next in a Datsun 200SX. Plugs were handled carefully, not dropped, etc.  Both were Champions. Since then, I'll use anything but Champions. Never had an issue with AC, Autolite, Bosch or NGK. Never did try to take one apart to see why it failed to work. Seems to me all it could be is an open between the electrode and the top (where the lead snaps on).

[Ted_Flash]

Modern plugs don't have their porcelain glazed because 1. modern computer controlled ignition/injection systems are so powerful and controlled they don't need it and 2. it saves cost.

So anyone running a vehicle with a less than accurate ignition system and a carb that pours neat petrol (full of anti-burn additives) all over its plugs should think themselves lucky their plugs spark at all.  Any electricity generated will much prefer to go through the stuff soaked into an coated on the plug nose.

I've had success boiling failed new plugs up in dishwasher solution, but n.o.s. plugs are the way to go if possible.

[shuswapkev]

yes you do get faulty plugs from new

heres a new NGk plug...put all new in my ford f-150 (300 six) when it was running a bit ragged.....ford reccos changing out plugs every 100,000 miiles...

this plug did maybe 300 miles...of which about 150...it didn't do any work at all...while I was changing out fuel injectors.....plug wires,  dist cap,  rotor..and..on and on

[shuswapkev]

maybe not the best picture but the porcelain is broken off ...all the way up...near exactly half of it

[Greybeard]

Erk! Do you think the engine chewed on the porcelain or did it exit, stage left?

[bikerbob]

I have had both Champion and NGK plugs fail, never straight out of the box but usually after a couple of hundred miles and you get erratic running. I was told by a dealer that the reason that my first set of NGK plugs failed was because I cleaned them with a wire brush and that with modern plugs because they are not glazed is sure recipe for failure why the second set failed I have no idea but since I now only clean my plugs with one of those contraptions with grit and compressed air both my bikes plugs have never let me down since.

[roadrocket]

Thanks all, I will look over the mag, slip ring brushes, HT leads etc. And try the old plugs. The only thing I did between a nicely running bike and current conondrum was the plus change.