Here's a bit of oddness. My FZR died one morning. I checked the plugs and they looked decent but there was no spark. Just as a control I put an old slightly fouled plug from my 550 in the boot and got tons of spark. Can plugs just die? All 4 of them at one time? Seems odd to me.
My test was with the electrode touching the engine.I made sure I used the same spot for both types of plugs and repeated the test 3 times with the same results.