Iridium Plugs

[Strom Strummer]

So, my 2016 1000cc Strom has Iridium Plugs fitted as standard. The service schedule in my owners manual says the plugs should be changed every 7,500 miles.

That's very frequently, especially for Iridium Plugs.  Why's that?

I know people will say they've completed many more miles than 7.5K on a set of plugs. I'm asking why we think Suzuki say change at 7.5K miles

Obvs the earlier MK1 bikes are a different kettle of fish

Thanks for reading ☺️

[porter]

I'm  not sure why they recommend  7.5k miles, I think they later changed it to 15k miles.
Anyway I leave mine to 15k miles and they've been fine. If they where easy to refit I'd put them back in but because so much has to come off to get to them I just replace while I have it apart. So it's safe to leave the plugs to 15k miles at least, I might try 20k on this set.

[Megashorts]

A revised service schedule was issued for L4 models onwards in 2015. The plugs are replaced every 15000 miles.

[kwackboy]

More money is made with frequent visits .. 

[Rixington43]

I put Iridium plugs in my Gen1 about 8k ago. I will probably replace them when I do my 30k valve service this winter but only because I'm confident they'll then last to the next 15k interval and I can't be arsed with the tear down in between valve checks.

[crump]

Are Vstroms hard on plugs? Seems quite low mileages.
Changed plugs (std NGK) on my old FJR at 36,000, 64,000. Put iridium in last time which so far have done 20,000. Bike was running well when I changed them all, only changed cos the piles were getting a bit thin.

[porter]

I don't think their any harder on plugs than any other bike, my last set looked fine at 15k miles. It's just there a pain to get to, so when I'm in there (every 15k) I'll relpace them. Rear cylinder is not to bad, plastic and tank off but to get to the front cylinder centre plug the radiator must come off, on a 2014 model anyway.

[Rixington43]

It's not quite radiator off on the Gen 1 but it's certainly more of a pain than the price of a pair of plugs is worth.

[pichulec]

Well I changed plugs for Iridium when the bike had 25000miles on the clock. Now it have almost 75000miles and still starting on the push of the button.

[Ian P]

G'day all, I will admit that I change my plugs when I check the valve clearances, at about 24-25,000 Klicks.
I use the common or garden non iridium cheap arse charlie NGK plugs and when they come out I reckon they would quite easily go again.
I also don't encounter any drop off of performance or fuel economy just before a plug change, or improvement after.

If I was facing the expense or inconvenience of changing every 7,500 Klicks I would 100% not bother.

However if you want to change your iridium plugs at 7,500 can I have the old ones please?

[timangus]

I had my plugs changed at 15,000 with a valve check. Now 64,000 and still runs fine with no further need to do anything. Might consider a valve check next year depending on where we end up riding to.

[Dark-Strom]

Non-iridiums last 20 to 40k in cars so iridiums should be an easy 50k in a bike I would have thought? My old Glee is still on its original 10yr old plugs, running sweet as ever, only 5k on the clock, they'll outlast the bike

[porter]

The 2014 on 1000cc vstrom uses a different spark plug than the older 1000 or 650. Its a bit smaller and longer reach and super expensive, well from a dealer anyway, cheaper online. Also only available in iridium.

[stevewestern]

Excuse my ignorance but what difference does an iridium plug make?
I assume that they last longer but is that it?

[Rixington43]

If you believe the marketing (and the physics/chemistry does add up) then they need less current to spark and they create a higher charge density due to the smaller electrode diameter. Some will say their vehicle starts a bit easier after adding them but, as with all things, there's no telling how much that is just down to fitting 'new' plugs rather than different plugs.

[Rusty Nuts]

Thanks for that, Rixington,  I never knew what it was about them that made them so different. 

[mr_diver]

the assumption that spark plugs will last longer in a bike is actually the opposite to reality.

Juvecu did a bit of research a few years back - most bikes to save the expense and weight of the type of ignition system on cars most bikes run with a wasted spark- basically a spark is generated when the piston is TDC regardless of where it is in the stroke sequence.

Effectively for a bike's plug fires twice for every 4 stroke cycle - where a car would only fire once.

if a car plug is good for 100k miles then a bike's plug is only good for 50k miles - then you need to factor in that most cars run on average far lower RPM at a given speed than a bike engine - So maybe 25k like for the bike spark plug.
(my wife's petrol car will be 3k rpm @ 70mph, my old wee would have been 6k rpm @ 70mph)

25k is still far longer than the 11k service life given in the manual though.

[pichulec]

Well, so how would you explain my plugs lasted already over 50000miles and still going strong?

[mr_diver]

Design life and actual life are different things.

Car service manuals generally say to change plugs around 25k. It's also about revenue for the dealers.

My Varadero plugs had done around 40k when I changed them, and at £29 a plug a few years back I won't be changing them again!

[Dark-Strom]

Design life = plug service interval = dealer money making bollards