Spark Plugs

[kennyw]

The CB 1100 takes special one off spark plugs designed for this bike. made by NGK they carry the designation LMAR8A-9S Honda part number 31908-MGC-003 and takes QTY 4. The bodies on these plugs are extremely thin as are the threads which are also extremely long at 26.5 MM or just over an inch.

The plugs are expensive at $19.99 each and it's highly unlikely your dealer will stock any so they will probably need to be ordered. A standard spark plug wrench is not going to work well given the small confines of the area to work in. However Motion Pro makes a thin walled 14MM narrow plug wrench that uses a 1/4" ratchet, a 13 mm box end wrench or a 14 mm box end wrench socket or T handle to loosen and tighten. It also has a rubber ceramic gripper up inside. Your dealer can get this from one of his suppliers or you can order it directly from Motion Pro

This pic illustrates just how small these plugs and tool are, On the left is a standard spark plug socket next to the Motion Pro Unit.
On the right is a standard spark plug next to the plug used in the CB 1100. Gap .031-.035 using a wire type feeler gauge is recommended.

L to R std spark plug socket, thin walled 14 mm Motion Pro spark plug socket, std spark plug, LMAR8A-9S spark plug for CB 1100

***EDIT*****
There is some question about whether these are correct or not. They have a different washer than the Honda-specific version. I would not order until it is determined if these will work

************

In case anyone is in the market, an Ebay seller with a lot of good feedback (not me) sells a 4-pack of these for just a shade under $26.00 including shipping:

[url=http://www.ebay.com/itm/4-pc-4-x-NGK-Standard-Plug-Spark-Plugs-4313-LMAR8A-9-4313-LMAR8A9-Tune-Up-wj-/121676142595]http://www.ebay.com/itm/4-pc-4-x-NGK-Standard-Plug-Spark-Plugs-4313-LMAR8A-9-4313-LMAR8A9-Tune-Up-wj-/121676142595

Not sure if this is a special deal or this is the price that these plugs have finally settled into, but I'm going to go ahead and buy a set to keep in my "someday" parts bin...

Are you sure that is the right part number? It is missing the "S" from the end of the number the ferret posted.

[the Ferret]

Oh man I didnt notice that. Hope they are the same, my set is already on the way lol

[Lord Popgun]

http://ngk-sparkplugs.com/lmar8a9s-p-2844.html

http://ngk-sparkplugs.com/lmar8a9-p-2843.html

Here are the spec sheets for both.

[the Ferret]

Well they are different, but all specs are the same. And the S suffix stands for " special gasket". hmm wonder what that means?

when they get here Monday I will compare them to the ones I have in stock and report back to this thread

[Redbird_imp]

Thanks Ferret, I have a set on the way also, so I hope they will work!

[Shinchan_imp]

I have a set on the way too. Sorry if I led anybody astray...

[the Ferret]

Ok my plugs came in today from the ebay seller (can't complain about the service lol) and I was able to compare them to the set I already had in stock. Identical..EXCEPT... the crush gasket as stated by NGK. The" S" on the specified plug from Honda does indeed mean special gasket

[url=http://smg.photobucket.com/user/theferret111/media/DSCF4177_zps2ri5nch5.jpg.html]

If you look closely at the plug on the right in the pic you can clearly see the difference in gaskets. The "S" gasket is both smaller in diameter and thinner than the one on the plug with the same designation without the "S" on the left.

[url=http://smg.photobucket.com/user/theferret111/media/DSCF4176_zpsekxgzqjm.jpg.html]

Now here's the thing.. I can't for the life of me figure out why that would make a difference? It must for some reason, but I have no idea why? Maybe takes less torque to crush the smaller ones? Maybe someone who has taken their old plugs out can explain it? or some engineer type?

I'm thinking about calling the ebay seller, Sixity Auto, to see what they have to say. They may have to go back.

[venturer434_imp]

Thanks for the pictures Ferret. I would be cautious installing this without knowing the difference in "S" and the impact it may have on the engine.. Just my thoughts...

[aschem_imp]

Found a website that sells the "S" version for $7.99

[Lord Popgun]

Great find Aschem! My dealer charges $18.95 per plug.