Murphy's law and chance.

[38racing]

Some of you may have read my threads on the tecumseh vtwin that I'm trying to get running on the white zt50. I seem to straighten out carb issues and had a 20 minute cut session and then lost some power. It was still running but not enough to power blades. After shutting down it was no start. Tests finally found blown head gasket on right cylinder. So I pull both heads, clean and and lap valves and put back together. Did a test start and it seemed ok but my temp gauge wasn't handy. Few day and I decided another start test before replacing air cleaner stuff. I added inline spark testers on each side so I could ground spark for testing.I find that left side is not running. During testing the sound changed and left carb started spitting back. I pulled left valve cover. Exhaust rocker off the push rod. To fix I pulled both plugs for easy crank rotation. Fixed and hopefully got the lock nut tight enough after setting valves again. Installed plugs. Fire it up and test shorts I find left cylinder now runs. Right does not. Pull its valve cover. Clearance might be a tad wide so I redo to .004. Compression test it. Over 100. Fire up and no change. Left runs. Right doesn't. Then I think. I remembered I just happened to switch sides on the first plug replace. Just because of how I picked them up. So I swapped the plugs. Now right runs. Left does not. Got a new plug for left side. Now both sides run. The failed plug was a new ngk. I originally had e3s that fit it but decided to go ngk. If I had not made that mental note about where I put the plugs who knows what other stuff I would have tried. I know I was thinking once again that I was back to carb issues.

[bobodu]

I was tricked by TWO bad brand new NGK plugs last year on a bike. Bought them at O'Rielly's Auto Parts and they were not counterfeit. Never had a bad NGK before.

[bgsengine]

I was tricked by TWO bad brand new NGK plugs last year on a bike. Bought them at O'Rielly's Auto Parts and they were not counterfeit. Never had a bad NGK before.

Yeah one of the biggest things with any spark plug is trusting in the source and its prior handling from the factory.. Just dropping a box of spark plugs on a hard concrete floor (knocking it off a shelf, etc) can introduce tiny hairline cracks you'll never see , even sometimes within the metal body of the plug, that result in a "bad new" plug out of the box.... which you may more often find when sourcing from auto parts stores, wal-marts, etc.. since their warehouse folks are, well, less well-trained.. I think the problems I used to see with Champion plugs were a lot to do with their packaging and material handling processes (dropping them off a conveyor during packaging, etc?) as well as the distributor I got them from (it wasn't just plugs that were often poorly packed, one example - packing a couple flat idlers sitting loose on top of some head gaskets, or packing heavy metal parts or box of saw chain in with more delicate (plastic/fiber intake tubes, etc) where things got crushed, smashed and knocked around in shipping.. I suspect that may be why it seems some brands have regional reputation since some regions served by the same distributor with poor material handling processes, etc.

[KE4AVB]

And it is a miracle that I don't receive more damage stuff from places like Amazon where they minimal packaging. But even the best package stuff can get damage during shipping. I have been at the UPS shipping center where I have seen package fall off the conveyor system and hit hard concrete than the workers just pick it back up and put back on the conveyor.

I personally package a $2000 programmable calculator and sent to Victor for factory warranty service. It didn't survive the shipment even I over pack it with factory foam plus additional foam. I even insured it which I got chewed out about until we had to file a claim with UPS. It had a Bakelite core frame that was completely shatter upon arrival at the service center. Still don't what happen during shipment as there was no external damage to the shipping carton; must have been a flat drop.

Considering how spark plugs are made even the assembly of the plug to metal shell can induce fractures if overly crimped. This probably why I have so many problems with the CMR 10mm spark plugs failing. Things like failure out the box, misfires, shorts, opens, and even had one that was causing dieseling in a hedger. So by all means when having ignition problems install known good test plugs. BGS more than once told us "New doesn't mean good".

[38racing]

Amazon doesn't even put head gasket between cardboards. Shipped me one in a big envelope that the post person folded.