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.

Further to my last:

I wasn't avoiding your questions regarding plug change intervals, just making sure my facts were right. In fact you are both right.

Firstly the Honda Shop Manual calls for plug REPLACEMENT at 8000miles and every 8000 thereafter. Inspection is at the 4000 mile intermediate services. This equates, to us tied to a metric system, to 12.8 thousand kilometres and every 12.8 thereafter for REPLACEMENT. Inspections at the 6.4k intermediate services.

The Honda Owners Manual calls for REPLACEMENT at 24000 kilometres and every 24000kms thereafter. Inspections at the 12000kms intervals.

Quite a disparity, to say the least. It's true that my shop manual is for the 2013 model but let's face it, a spark plug is a spark plug when its the same plug for the '10 through '13 models (NKG LMAR8A-9S).

The Honda dealer's service manager, mine anyway, likes to follow the shop manual intervals. Keeps the stock turning over I guess. I would have one message for him:





Cheers

[Cormanus]

Love The Castle.
By the way, my plugs got replaced at about 15,000 kms as my 12,000 km service was delayed while I rode about the place with Pterodactyl. The mechanic told me the ones he replaced looked pretty good. He wasn't sure why he replaced them. They were very expensive too.

[furious_blue_imp]

I agree. And I think they should be able to last a lot longer than the change interval listed. If my lowly Toyotas can have 100K mile plugs, why not a premium Honda motorcycle?!

my guess: typical car engines probably run at lower rpms than motorcycles. That means the the plugs in the car fire less often per mile so that might mean that they last for 'more miles' for the same number of times being fired.

[Pterodactyl_imp]

I agree. And I think they should be able to last a lot longer than the change interval listed. If my lowly Toyotas can have 100K mile plugs, why not a premium Honda motorcycle?!

my guess: typical car engines probably run at lower rpms than motorcycles. That means the the plugs in the car fire less often per mile so that might mean that they last for 'more miles' for the same number of times being fired.

my guess: typical car engines probably run at lower rpms than motorcycles. That means the the plugs in the car fire less often per mile so that might mean that they last for 'more miles' for the same number of times being fired.
You are right. See post #26

Quote: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.
Cheers

[flynrider]

I have never had a plug break down and misfire. I replaced the plugs in my ST at 25,000 miles but the plugs that came out looked just like the plugs that went in. Many on the ST board run them 50,000 or more.

I suspect I will inspect the ones in my CB at about 20,000 miles, unless it starts misfiring, or gets hard to start, or my gas mileage drops off.

This is what I've always done. I pull 'em every few years to clean and gap, then put 'em right back in.

The CB750's stock plugs went 25K miles. The electrodes still looked fine, but one of the plugs developed a hairline crack in the ceramic and started to misfire.

[linuxology_imp]

sorry to necrothread, but what are the gap specs on the plugs?

[the Ferret]

I think .031. Popgun verify? I am putting in my set on Tuesday at 26,000 miles. Will try and do a pic tute.

[Lord Popgun]

And the manual says: 0.80-0.90mm (0.031-0.035 in)

[the Ferret]

Why do they give you a range. Why not .033 or something? I hate making decisions lol

[Lord Popgun]

LOL Hey, I just quote the manual, not write it...