Spark plug nerding
Dan
I prefer NGK's, then Bosch. Most motorcycle manufacturers contract with Denso, as does Toyota as you mention. Aftermarket Denso, they seem to want to go "split-fire" in marketing iridiums with that goofy grooved ground electrode design. I prefer to feel I'm more educated to buy into that? Watching the german force induction motors, NGK iridiums started becoming OE equipped, with the advent of individual coil ignition systems. I suspect this is due to the fact that individual coils could probably arc voltage across a electrode made of a rock, and they will eat up silver, copper and even platinum electrodes at a higher rate than iridium.
Shaun
It gets a lot nerdier to really explain gapping fully. A topgap single ground electrode copper or silver plug is meant to be gapped/regapped. A sidegap multiple ground electrode plug is not designed to be gapped/regapped. An iridium or a platinum plug is not designed to be gapped/regapped. I'd say generally "Gapping down" a better plug design is unnecessary due to the better plug design.
Tapage
Mileage is a tough call, I'm not sure I could get into all the variables. My suggestion is that one pull a random plug every 10k, and ck it to the pictures on the web. IME with iridiums and platinums, unless I suspect spark plugs in ignition diagnostics, I just pick a conservative service interval. IME, multiple pulls/installs of platinums (especially) can cause the tip to get dislodged (can't explain it, but a known entity on even the expensive bosch platinums).
HTH and my .02
Scott J
94 FZJ80 Supercharged
BKR6EIX Iridiumed
Dan
I prefer NGK's, then Bosch. Most motorcycle manufacturers contract with Denso, as does Toyota as you mention. Aftermarket Denso, they seem to want to go "split-fire" in marketing iridiums with that goofy grooved ground electrode design. I prefer to feel I'm more educated to buy into that? Watching the german force induction motors, NGK iridiums started becoming OE equipped, with the advent of individual coil ignition systems. I suspect this is due to the fact that individual coils could probably arc voltage across a electrode made of a rock, and they will eat up silver, copper and even platinum electrodes at a higher rate than iridium.
Shaun
It gets a lot nerdier to really explain gapping fully. A topgap single ground electrode copper or silver plug is meant to be gapped/regapped. A sidegap multiple ground electrode plug is not designed to be gapped/regapped. An iridium or a platinum plug is not designed to be gapped/regapped. I'd say generally "Gapping down" a better plug design is unnecessary due to the better plug design.
Tapage
Mileage is a tough call, I'm not sure I could get into all the variables. My suggestion is that one pull a random plug every 10k, and ck it to the pictures on the web. IME with iridiums and platinums, unless I suspect spark plugs in ignition diagnostics, I just pick a conservative service interval. IME, multiple pulls/installs of platinums (especially) can cause the tip to get dislodged (can't explain it, but a known entity on even the expensive bosch platinums).
HTH and my .02
Scott J
94 FZJ80 Supercharged
BKR6EIX Iridiumed
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