I've got a few questions regarding spark plugs!

[huck farley]

Can some one tell me what on average is the life of a spark plug nowadays. Particularly in a big bore, multi cylinder engine for touring? (not commuting)

Also what in your opinion is the best make of plug to screw into the head. regardless of price, and why? (touring)

Last one: What would one have to pay for say a middle to upper range Spark plug for a multi cylinder engine? (touring)
cheers all
Huck

[YellowDog]

Great question. I thought that provided they are clean and the gap is consistent, they lasted forever. I guess if they get physically damaged, they won't be up to much. I always found that the HT leads needed changing before the plugs.

All this shows how out of touch I am with the workings of a modern engine. Must start reading up on this or something.............

[avgas]

i found i roughly got atleast 10x the ammount of k's on iridiums in comparision to standard plugs. In all my engines.
Best i got from standard plugs - 15,000K's
Worst - 5,000K's
I never had to replace iridiums.

[scumdog]

My spark-plug experience?

20,000+km in CBs Sporty and still going.

22,000+km in the T-Sport and still going.

I have a look at them about once a year and chuck them back in, standard issue HD plugs btw.

In the days of leaded gas they didn't seem to last as long.

[Cajun]

i found i roughly got atleast 10x the ammount of k's on iridiums in comparision to standard plugs. In all my engines.
Best i got from standard plugs - 15,000K's
Worst - 5,000K's
I never had to replace iridiums.

i noticed the difference when i replaced the iridums in the 600 after 25,000kms (normal plugs meant to be replaced ever 12,000).

[Katman]

One thing to bear in mind with motorcycle spark plug longevity is that (in a four stroke) they fire twice every full cycle as opposed to a car where they only fire once.

[scumdog]

One thing to bear in mind with motorcycle spark plug longevity is that (in a four stroke) they fire twice every full cycle as opposed to a car where they only fire once.

EH? eh? eh?

Harleys fire both plugs at the same time (unless you fit a single-fire kit) but the rest???

[Katman]

EH? eh? eh?

Harleys fire both plugs at the same time (unless you fit a single-fire kit) but the rest???

Motorcycles don't have a distributor. The pick-up that sends the signal to fire the plug each time the crank turns 360 degrees isn't clever enough to know which TDC stroke it is on.

[scumdog]

Motorcycles don't have a distributor. The pick-up that sends the signal to fire the plug each time the crank turns 360 degrees isn't clever enough to know which TDC stroke it is on.

A lot of cars (actually most these days) don' have distributors either but the crank still only fires each cylinder in turn on the firing stroke only.

[Sully60]

Motorcycles don't have a distributor. The pick-up that sends the signal to fire the plug each time the crank turns 360 degrees isn't clever enough to know which TDC stroke it is on.

That's not entirely true, modern ECU's do all sorts of funny things with ignition timing. Have you pulled the ignition trigger rotor off a late model 4 cylinder fuel injected bike?

To answer the original question the manufacturers were stating (early naughties) the plugs fitted from the factory in the modern fuel inject bikes are designed to last the life of the bike.

Tell that to the people who buy big sports bikes and use them for inner city commuting

[huck farley]

i found i roughly got atleast 10x the ammount of k's on iridiums in comparision to standard plugs. In all my engines.
Best i got from standard plugs - 15,000K's
Worst - 5,000K's
I never had to replace iridiums.

I have 22000ks up and they have never been out. That's why I posted if anyone new the life span of the modern day plug. Looks like they go forever. I guess time will tell aye?

[huck farley]

i noticed the difference when i replaced the iridium's in the 600 after 25,000kms (normal plugs meant to be replaced ever 12,000).

What price do the iridium plugs work out to per plug? Just an educated guess will do. Also what's the difference between an ordinary plug and the Iridium? (besides the price)
Cheers
Huck

[koba]

What price do the iridium plugs work out to per plug? Just an educated guess will do. Also what's the difference between an ordinary plug and the Iridium? (besides the price)
Cheers
Huck

Ive paid from 16-25 bucks for them, well worth it in my experiance, they are supposed to take a bit longer to get up to temp to work just right: noticable in my old jap turbo car but never noticed any difference on a bike.
They use a bit of iridium on the very pointed tip, doesnt wear out from sparking like a normal plug. They come pre gapped, dont try to gap them!
Mine have been good for ages.
Maybe they make it go better too but my arse dyno can't tell the difference.
I read somewhere that the 2x firing from wasted spark that katman mentions above is meant to help clean the plug between cycles too.

Abit rambly above but its friday night ...

[avgas]

I have 22000ks up and they have never been out. That's why I posted if anyone new the life span of the modern day plug. Looks like they go forever. I guess time will tell aye?

I suggest you best have a look at em - they prob work but dont look so pretty anymore. From recall the 955i i used to ride got about 20,000 and then fuel economy was noticeably worse on standard plugs.
Funny thing is for the yamaha:
Standard plugs - $22
Iridiums - $26

22000 on a 1050 - that must have been through at least 3 triumph dealer services by now, didn't they change the plugs then?

[avgas]

Mine have been good for ages.
Maybe they make it go better too but my arse dyno can't tell the difference.

Not even in the RG150's? as i noticed a huge smooth power delivery on mine with iridiums.
Also ment i could run avgas on it with no issues.