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Iridium spark plugs


Paul4450

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I've seen threads on other forums regarding using iridium spark plugs vs the OEM conventional ones. One plug mentioned is the NGK LMAR9AI-8. Does anyone on this forum have any experience and/or comments?

 

My rationale of considering iridium plugs is more consistent plug performance over a longer period of time and miles. I've read some claims about improved starting (possible, I think), smoother running (maybe if old plugs were worn), different sound from exhaust (huh?), and probably others. Those are non-issues for me.

 

Thanks!

Paul

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I don't even remove my spark plugs. My Suzuki car has now done 55k, starts and runs as smoothly as ever and returns as much mpg as ever. Triumph 1050 Sprint 15k and second car similar without problem. However, I can remember the days of leaded fuel when spark plugs had to be removed, cleaned or replaced regularly. As they say you pays your money and makes your choice. You're unlikely to notice any difference except for a placebo effect and you certainly won't see a return on your outlay.

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I've seen threads on other forums regarding using iridium spark plugs vs the OEM conventional ones. One plug mentioned is the NGK LMAR9AI-8. Does anyone on this forum have any experience and/or comments?

 

My rationale of considering iridium plugs is more consistent plug performance over a longer period of time and miles. I've read some claims about improved starting (possible, I think), smoother running (maybe if old plugs were worn), different sound from exhaust (huh?), and probably others. Those are non-issues for me.

 

Thanks!

Paul

 

Morning Paul

 

The specs show them close (assuming your 1200RT now uses the NGK LMAR8D-J Plug).

 

One number difference in heat range so the NGK LMAR9AI-8 is a slightly colder plug.

 

The NGK LMAR9AI-8 would probably work OK but I wouldn't recommend using it if your 1200RT is still under warranty as it ISN'T the correct spark plug for your engine.

 

Just make sure the NGK LMAR9AI-8 doesn't come too close to the piston as it's electrode configuration is different so I would imagine it extends into the combustion chamber a bit further.

 

sFmus6E.jpg

 

 

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Hi DR!

Thank you. As usual, you have provided great information! I have a ‘14 RT, so no warranty issues. The advrider forum has several GSW riders using the iridium plugs, with no apparent problems with clearance. Plus someone asked an NGK tech about using iridium and it was the tech who confirmed the iridium equivalent and recommended the colder plug. There are some comments regarding the heat range as well, with some saying the colder heat range is “better” since the plug is “deeper” (by 1.5 mm) in the combustion chamber. But my thinking says because the center electrode is in the same spot and it's the center part, the ceramic part that “controls” the heat range, that DR would be correct to use the LMAR8AI-8 iridium instead. On the NGK site, they are a few cents less expensive vs the 9 heat range plug! $11.46 vs $11.50 each! Bonus! The NGK site has the best prices that I've found, as mentioned in the advrider forum link. Beemer boneyard wants ~$29 for a pair of OEM plugs. I would imagine a dealer would charge even more.

 

I've got a dial indicator to check combustion chamber clearance but probably don't have the proper threaded adapter. Worked great on my ‘76 RD but these plugs are a lot different in dimensions! Since the R1200W head is a 4 valve head with a center located plug, and others have used them, I'm not anticipating clearance issues. I suppose I could just insert a rod into the spark plug hole and see how deep the combustion chamber is. I can use the spark plug and spark plug hole to get reference points.

 

Regarding Pickaxe's comments, the maintenance schedule calls for plug replacement every 12K miles. I am surprised and disappointed that the conventional plugs show visible wear after just 12K miles (hence need changing). I agree with Pickaxe that other vehicles show minimal spark plug wear over much longer intervals, but it seems that for whatever reason(s), the R1200W motor eats plugs quickly. If Pickaxe has an R1200W motored bike (be it an R, RT, RS, or GS), he/she may want to pull those plugs if it has more than 12K miles. I am nearing another 12K mile interval, and while it may have always been there, I do notice an occasional “skip” in the idle currently. Like I said, I'm not expecting miracles.

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I have the NGK LMAR9AI-8 in my 2017 R1200GS. No issues at all. Wear after 6000 miles (12k on the odo) was not noticeable. I will be checking them every 12k, but I expect them to last at least 36kmiles.

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Paul4450, I will certainly take your advice on this occasion and check the plugs. I've only completed 8k in the first year, so will probably wait another year or unless I notice running issues.

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