Spark Plugs

[Pterodactyl_imp]

Ptero...that's like 24,000 miles isn't it? Doesn't Honda call for replacement at 8,000 miles (13,000 kms) or is that just an inspection?

My manual says inspect at 12,000 kms (7,500 miles), replace at 24,000 kms (15,000 miles), inspect at 36,000 kms. It gives up then.

Guys I didn't make myself clear. Honda did the 12000 and 24000 (km) services and changed, and charged for, the plugs. The bike was under warranty. My bike is now at 38000kms. However, if those NKGs can only handle 12000kms, or even 24000kms, then I'll be one of those ring-tailed whatchamacallits. After 16000kms since being changed, the electrodes are not worn, the insulators are intact and not discoloured, the gaps are still perfect and the colour of all plugs is good. Why change? I will have another look in another 6000kms but, even then, unless these plugs are not built to last, I would expect to see considerable life still left in them.

My experience with plugs tells me that if the electrodes are in good condition and the insulators are not cracked (normally by heavy handed changing, but also by heat) then the plug is as good as new. A good quality plug (platinum) should last anywhere between 30000 to 60000 miles and iridiums up to 120000 miles. High performance (revving) motorcycle motors and heat intense motors (as in air cooled maybe) may reduce the life of platinum plugs to maybe 20000 miles. Race bikes, for obvious reasons, to much less. But the CB hardly fits into those categories. As for heat control, I guess that is one reason that Honda oil cooled the galleries adjacent to the plugs. Plug wear should first become apparent by the rounding off and then erosion of the tip of the centre electrode. I don't see any evidence of that on my 12000kms old plugs. Polish them up, wrap them in tissue, put them in a box and you could sell them as new.

However, maybe I am being pennywise and pound foolish. Maybe not built to last is a factor. But I think NKG would dispute that. The Honda service manager might have a different view. Ferret, you have done a lot of miles in modern bikes, have you ever had a plug breakdown? Anyone else? Tell me what you think?

Cheers