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spark plugs

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petrolderek:
Has anyone else had any problems with new spark plugs. I have worked with engines all my life and am now retired so I have had quite a bit of experience but in the past few years I have had loads of problems with new plugs breaking down. I have a 305 dream and its on its third set of new plugs and its not done 100 miles. Today I started my Yamaha yds5 and it was misfiring on the right cylinder checked the plug and there was no spark changed the plug for one that was in the bike when I got it that must be 30 years old and its fine. These plugs in the Yamaha were new a month ago. Checked the plugs resistance and its showing 30k but the old ones show OL. So what's happening any ides the only thing I can think of is I have had them in and out quite a few times when I had a piston ring problem could it be taking them out when hot or just handling them is causing the problem.

murdo:
I've had similar problems with new plugs. Remember when you had to save up your pocket money to buy a new plug for your paddock basher? These days the plugs are made cheap and cost about the same as 1/2 cup of coffee.
Suggest you look for some old stock plugs. I found two Champions in USA for my YDS5 that ran better than the NGKs I could by at local shop.
Still have some Belgium and German made Champions for my Maico. They would last for a couple of years of hard riding where as the NGKs might last a day.

TGR90B:
A couple of years ago there were a lot of fake NGK plugs on the market. Perhaps some are still about, but not a problem I've heard of recently. Have you tried Bosch plugs?

iansoady:
As I understand it, older plugs had a "gloss" finish to the insulator nose inside the body of the plug, which allowed for cleaning. Modern ones have a matt finish and once fouled are almost impossible to clean so are effectively scrap.

Rex:
I'd go along with that. If new plugs get "wetted" under the nose insulator it seems they can't be cleaned effectively any more. The so-called Green Spark Plug Co refused to replace two 18mm plugs which failed from the first start-up as they said I'd put the plugs in a cold engine and "wetted" them. They couldn't explain what I should have done  with an engine which hadn't run in decades and this was the first start.....
It seems amazing to me that old bikes and cars carried the owners to work without any problems but cossetted classics seem to have failing plugs on a regular basis.

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