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I am just about ready to do the 12k miles maintenance on my 2021 RT, and I thought that I would share something with the community that should save some money for those who also do their own maintenance. The major differences between the 12k and 6k miles maintenance are that for the 12k miles, you need to change the FD oil, which is extremely simple. Next, you are supposed to change the air filter, which is somewhat of a PITA, since lots of fairing and trims needs to be removed, but otherwise quite simple. Of course, you also have to do the valve clearance check. The last big thing that one is supposed to do is to change the spark-plugs. This last part is what this thread is about!

BMW specifies Iridium spark-plugs for the 1250 boxers. Specifically, the NGK LMAR8AI-10. The very first question that some will ask right away is why change at only 12k miles? That's an iridium plug, and it should last for at least 50k miles! Good question, and partial answer from me is that, it's what BMW specifies, and if you want to make sure that BMW have absolutely no reasons to deny you any potential warranty service in the future, then you should make the change, and keep the old plugs off the bike for future use if they looks to be OK. Keep reading. There some more data on this later.

The next question will come when you start shopping for the specified plug. Wow, why so expensive??? It seems that this plug is only used for the 1250 shiftcam boxers, as far as I can tell. Buying the plug from BMW dealer will cost you more than $30 each, in the US (our friends in the UK and EU countries have it at much lower price). Even Beemerboneyard, who usually have much lower price, is selling them for $54.38 per pair. The best price that I had found was here: Iridium Spark Plug - BMW R1200 2017on R1250; 12 12 8 560 811 / LMAR8AI-10 / NGK for $21.99 each. Can I do any better than this?

Well, in looking around I came across this: NGK LMAR8AI-8. BMW specifies it for the K1600s, and this plug is much cheaper. Best price that I have found was here: NGK 92288 LMAR8AI-8 Laser Iridium Spark Plug at $12.79 each!

So, what is the difference between the 2 plugs, since from the part number, that difference is in the last -10 vs -8. What does that really mean? It turns out that the two plugs are the same plug, with the -10 having the electrode gaped at 1 mm from the factory, while the -8 are gaped from the factory at 0.8 mm. Just for an FYI, here are the meanings of the rest of the NGK part number, specifically as applied to the NGK LMAR8AI-10 :

L- Plug Type Thread Reach: 26.5mm
MA- Metal Shell
R-Resistor
Heat Rating Number 8
A
-Firing End Construction Special Design
I-Firing End Construction Single Iridium Spark Plug

Stock Number - 94319
Type - Laser Iridium
Plug Diameter = 10mm
Thread Length = 26.5mm
Hex Nut = 14mm
Heat Range = 8
Resistor = YES

How you use the above information is up to you, as always! It's your bike. However, should you decide to buy the -8 and open up the gap to 1 mm, then I should caution you to be very careful in how you do that. The center iridium electrode is very thin and delicate. You absolutely need to use the proper spark-plug gaping tool to do the job.

Last note is that, I always refer to posts in Adventure Riders Forum for accurate technical information. Those guys are very much more knowledgeable in the technical areas than in any other forums. I had discovered the meaning of the dash-number from there, specifically from this thread: 2019 R1250GSA Spark Plugs/Unicorns? I think that it's worthwhile for you to at least scan over the posts. Now, back to why you might want to consider changing the plugs as early as 12k miles, or at the very least give them a very good examination keeping your riding environment in mind, you need to read post #71 on page 4.

Ride safe!
 

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Are the splines supposed to be inspected and lubed at both 6k and 12k then?
Did something change for 1250 models? Wasn't necessary for prior wethead models, in general.
 
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Already shared here about 9 months ago in post #578.
 
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Do you have the 8mm TDC pin, cam shaft chain tensioner and the proper shift cam bridge gauge for the ends of the camshafts to make sure your cam timing is correct. Doubt it. This gear is needed to do a complete valve check. I suspect the clearance will be just fine but not too sure about the cam timing as many things have settled in after 12K miles. (let alone, the proper procedure for removing the electric solenoid for the placing of the bridge gauge. Damn BMW will not sell you the DVD service manual which keeps you out of trouble.) You worry about warranty and then do not follow all the complete and described procedures for the service.
 

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NGK runs different in heat ranges. A 6 is hotter then a 8 in NGK plugs. I would be sure of my information before changing the heat range on my motorcycle.
From NGK:
"
Understanding Spark Plug Heat Range

One of the most misunderstood aspects of spark plugs – is the heat range. One misconception is that the heat range is related to the spark temperature or intensity. Another common misconception is that the spark plug is designed as a heat sink to “remove” heat from the combustion chamber. These ideas are both false. The spark plug is heated during combustion and must dissipate that heat to the cylinder head at a certain rate to avoid overheating the ceramic firing end. The spark plug heat range only indicates the rate that the spark plug dissipates its firing end heat to the engine.
A hotter heat range spark plug has an insulator design with a longer heat flow path to the metal shell of the plug. As a result, more heat stays in the ceramic firing end and less is dissipated to the engine. A colder heat range spark plug has an insulator design with a shorter heat flow path to the metal shell of the plug. As a result, less heat stays in the ceramic firing end and more is dissipated to the engine. For a spark plug to function properly, it must have a tip temperature high enough to burn off carbon deposits (self-cleaning) and avoid fouling, while remaining low enough to avoid overheating the ceramic firing end and pre-ignition.
For most vehicles, the factory recommended heat range is sufficient; however, on some modified or special-use engines, alternative heat ranges may be necessary. Often hotter heat ranges have been used to address a fuel delivery or oil consumption problem. Installing a hotter heat range plug will reduce the pre-ignition safety margin, so it is better to correct the mechanical or tuning issue instead of changing the plug heat range."
 
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Discussion Starter · #8 ·
Are the splines supposed to be inspected and lubed at both 6k and 12k then?
Ahhhhh . . . . the "lube-the-spline" myth!!! I have been fighting this myth, quite unsuccessfully, for many, many years now! The spline on the 1200 and newer boxer do NOT need to be lubed at all. This myth came about from the spline destruction on the 1100s and 1150 boxers. Without going into the details (I could, if you are that interested), those riders, without help from BMW, discovered the root-cause of the problem and came up with the work-around to prevent spline stripping by frequent inspection, and more important, application of lubrication.

BMW did a complete redesign of the drive-train when they came out with 1200 boxers. The issues experienced with the 1100s and the 1150s no longer exist. You can go ahead and take the drive apart if you want to, since lubing a part that doesn't require lubing isn't going to hurt it, however, DO make sure that when you put everything back together again, that you seal the joints at the boot really well. BMW specifies specific compound to seal the joint, and at the very least make sure that you do use it! Why? Water incursion into the inside of the drive housing is your biggest enemy.

You can do all the searches that you like, and you will find that there have been ZERO spline failures for any 1200 and newer boxers, while there have been quite a few u-joint failures! I came across the discussions on the AdvRider forum back around 2014, or perhaps earlier. From the pictures that I had seen of the failed drive u-joints, I knew right away what the cause was. One common denominator that I saw in the pictures were rusty components. U-joints have needle roller-bearings, and these bearings are lubricated with grease. It seems that BMW uses bearings that isn't sealed nor can it be externally lubricated. As for the water, I won't get into the technical explanation, but you can Google the details yourself, if you want to get into the details. Google the term "bearing grease water contamination", and you should get plenty of technical explanation of what water does to the bearing lubrication.

I rarely post on the AdvRider forum, but I did that time. I am not sure that many people believe me at the time. I also posted similar things here, which you should be able to find if the archive kept here goes back those many years ago. Now, let's talk about today!! Did you know that within the last couple of weeks or so, BMW have issued a notice of recall for a lot of 1250 GS/GSA? Apparently, they are concerned about the drive-train, and they want to "inspect" the drive-shaft for "damage", and "install" a vent/drain hole with one-way valve into the drive housing! Gee, I wonder why??? Finally, they recognize the issue??? Here is a link to one source for that news (there are many more): 440,000 BMW GS Bikes To Get An Extra Test At Their Next Inspection Of course, this applies to all 1250 boxers, including our RTs.
 
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Discussion Starter · #9 ·
Do you have the 8mm TDC pin, cam shaft chain tensioner and the proper shift cam bridge gauge for the ends of the camshafts to make sure your cam timing is correct. Doubt it. This gear is needed to do a complete valve check. I suspect the clearance will be just fine but not too sure about the cam timing as many things have settled in after 12K miles. (let alone, the proper procedure for removing the electric solenoid for the placing of the bridge gauge. Damn BMW will not sell you the DVD service manual which keeps you out of trouble.) You worry about warranty and then do not follow all the complete and described procedures for the service.
Why would I need them? As far as I am concerned, cam timing needs to be checked ONLY because of BMW's screw-up on their production floor, and bikes were delivered with them being off from where it should be. If I want cam timing done, I would have my dealer (with extremely competent tech, and lower hourly rate than the typical BMW dealership) do it. It's a one-time check, and not a regular maintenance routine.
 
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Discussion Starter · #10 ·
Lee, that's why I recommend that people at least scan over the posts in the AdvRider thread that I had referred to in my original post. The full explanation is in there.
 
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Discussion Starter · #11 ·
Already shared here about 9 months ago in post #578.
I must have just skimmed over the post at the time!
 

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This myth came about from the spline destruction on the 1100s and 1150 boxers.
Incorrect. I had a CLC. That is a 1200 (1170 cc) Oil-head. That, and all other C bikes had the spline problem. Check on Chrome-heads forum.

I believe what actually happened was a design change beginning with the Hex-head (cca. 2005).
 

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Discussion Starter · #13 ·
Incorrect. I had a CLC. That is a 1200 (1170 cc) Oil-head. That, and all other C bikes had the spline problem. Check on Chrome-heads forum.

I believe what actually happened was a design change beginning with the Hex-head (cca. 2005).
You are correct! I had forgotten about the CLC. The design change did start with the hexhead. The design of the FD also changed with the hexhead in 2005. Before that, the design of the FD is identical for the KLT (and the K-series) as well as the earlier boxers. The root-cause for those FD failures were identified right here, in this forum.
 
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Splines in the U joint slide over the internal and external cuts, lube sure helps as there is serious metal to metal contact. Why not keep things smooth and a little cooler. Also it is possible for water to enter, a lube will help prevent corrosion. Maintenance is to prolong life not all maintenance is listed in BMW documents. With chain stretch, sprocket and gear wear, general bearing and fit wear, the cam timing changes. One symptom is slow starting.
 

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You can do all the searches that you like, and you will find that there have been ZERO spline failures for any 1200 and newer boxers
I don't think this is true. There is a member here who had his 2019 final drive replaced under warranty. He found it rusted and seized at 8000 miles. That isn't the first one I've read about. Boxflyer has mentioned upon first inspection he's found the final drives rusting as well. Most likely not sealed correctly from the factory. Seems like a good reason to inspect and grease it as a maintenance item, especially resealing the boot.

 

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Well I am really surprised no one has started a thread on the Service Campaign on GS/GSA/Police RT's. They are putting a vent in which is worthless. The splines need lubed, PERIOD. New post in the link where they just replaced a drive shaft on a 2018 GS. I have seen MANY FD/DS rust welded. MY 15 RT was dry and my 17.5 was dry.

Read this thread and know it is not use or abuse causing this, it is no lube on the splines.
Service Campaign for Vent install.

And Jim from JVB Productions has advocated spline lubes since I had my 2015 RT. He has a 96 page threadfest on the above Forum that he posted public in 2016. It is bare metal sitting in there, with normal condensation cycles, just rusting away that bare metal BMW sent to us in our drive shafts.
Final Drive Lube Pictorial By JVB
 

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Discussion Starter · #17 ·
I don't think this is true. There is a member here who had his 2019 final drive replaced under warranty. He found it rusted and seized at 8000 miles. That isn't the first one I've read about. Boxflyer has mentioned upon first inspection he's found the final drives rusting as well. Most likely not sealed correctly from the factory. Seems like a good reason to inspect and grease it as a maintenance item, especially resealing the boot.

The spline didn't fail, and the fact that it rusted together solid, proves the point that I have been making all along over the years. The new design of the drive is such that the mating splines do NOT move with respect to one another! IF they were moving, they wouldn't have been able to be rusted together! So, lubrication doesn't do a thing! I know the thread that you are talking about, and if you will look back at that thread, you will find that I was quite involved in the discussions! He had found the seized (fully rusted) spline only because the u-joint had failed!! If it's the same thread I am talking about, the guy made the repair himself, and went one step further by drilling a drain hole in the housing! That is, until I had pointed out to him that the plain "drain-hole" is not such a good idea, since the housing will heat up some, as you ride, and the air inside will expand and vent. As soon as you ride through a puddle, the housing will get a sudden cooling, and actually will suck in any water outside the drain hole! He wisely plugged up the hole that he had drilled! [Now BMW is going to do the very same thing, BUT will also fit a one-way drain valve! Our guy had the right idea at the beginning!!]

The other thing that he did wrong was to use the spline-lube grease to seal his boot instead of the BMW specified compound, which I had also told him about. A few weeks later, he reported that while riding though pouring rain, he went through a big puddle. On checking later, he reported that he had drained out about 1/2 cup of water from inside the housing!

So, I will repeat what I said many times in the past - IF you do get inside the drive housing and see rust, take that as a serious warning sign. Saying that lubing the spline just so that it doesn't rust is pure ignorant!
 
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BMW did a complete redesign of the drive-train when they came out with 1200 boxers. The issues experienced with the 1100s and the 1150s no longer exist. You can go ahead and take the drive apart if you want to, since lubing a part that doesn't require lubing isn't going to hurt it, however, DO make sure that when you put everything back together again, that you seal the joints at the boot really well. BMW specifies specific compound to seal the joint, and at the very least make sure that you do use it! Why? Water incursion into the inside of the drive housing is your biggest enemy.
Got it, so it's not an issue of lubrication - it's an issue of water penetration along with all the associated issues with water... water + grease, water + air = rust... etc.
 

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Discussion Starter · #19 ·
Got it, so it's not an issue of lubrication - it's an issue of water penetration along with all the associated issues with water... water + grease, water + air = rust... etc.
You got it! The most serious issue is the water+grease. If you did the Google search, you will see that's what causes the bearings to fail. Lube the spline if it will make you feel good, and whenever you like, since you are not going to find anything from BMW to tell you to do that.
 

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Of course, you also have to do the valve clearance check. The last big thing that one is supposed to do is to change the spark-plugs. This last part is what this thread is about!
For what it is worth on the 12,000 mile valve check and spark plug replacement.

I just had this done by my local BMW dealership. I clarified with the mechanic that they would check the cam timing prior to valve lash check and he indicated "yes that has to be done first". Now I did not have an opportunity to supervise his actions that he actually did it, but he was at least knowledgeable about the process and BMW tools required to check it.

Spark plug BMW# 12128560811 $ 27.72/ea
Valve lash adjustment with cam timing checked $105
Total cost out the door $170 with tax/shop supplies

Font Rectangle Parallel Screenshot Electric blue



I have no idea if they put in the correct plugs in nor did I receive the old ones back. I also don't have any guarantee that they checked the cam timing nor adjusted the valves correctly. l took my chances on BMW maintenance from a BMW certified dealer that I typically would always do myself but wanted the receipt for warranty purposes and the price was within reason. Time will tell...
 
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