Review on NGK (6289) CR9EIA-9 Laser Iridium Spark Plug, Single Pack by Ricky Snyder

As far as I know NGK is the leader in the line. I think Iridium is at the top of that list. The price was very good, especially with free shipping. This part is great! The only thing is that after about 3 hours of operation of this candle, a crack or defect formed in the central ceramic insulator, as a result of which the spark disappeared. Ran a few days to find better than new. But then it started to misfire and was hard to start (500cc utv); If the spark plug was removed and pressed against the engine during cranking, you could see the spark travel from the center electrode directly across the center ceramic instead of jumping across the gap. It was a return after a short warranty period so it was refused. This is a very rare problem so I'm wondering if these are class A plugs from the factory or if there is something that makes them prone to problems. It was sent in a small package with a layer of bubble wrap around the box, but was initially undamaged. So who knows? I would probably buy it again but that's just my real story.