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How To replace your Spark Plugs
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The ferret Online
Forum Moderator

Ohio
Posts: 18,758
Joined: Apr 2013
Post: #1
How To replace your Spark Plugs
Honda Service manual calls for inspection every 4,000 and replacement every 8,000 (Which is just nuts IMO) but that’s what the manual calls for. I inspected and replaced mine at 26,000 miles. The bike was still starting and running good and fuel mileage hadn’t gone down but I have come to replacing plugs and air cleaners every 25,000 miles on my Honda motorcycles out of habit/personal experience. Use your conscious as your guide or be safe and follow the manual’s recommendation.

These are special plugs, very skinny, very long reach and with a special sealing washer, which we have discussed at length here:

http://cb1100forum.com/forum/showthread....park+plugs

Tools needed:
Air hose with spray nozzel
Stock Honda spark plug wrench or Motion Pro equivalent (what we are using here)
14 mm box end wrench
Spark plug gapping tool
4 Honda Spark plugs LMAR8A-9S Honda Part Number 31908-MGC-003

Start by putting the bike on the center stand. We started on the left side of the bike but that really is unimportant.

First thing you need to do is check the gap on the new plugs. Spec calls for .031-.035. Mine all came out of the box from the factory at .033. We re-gapped them to .031 to allow for wear down the road.

İmage

Take an air nozzel and spray the outside plug cavity to remove any debris. We don’t want any of that falling into the spark plug hole once the plug is removed.

İmage

Take off the outside spark plug cap and slide spark plug tool over the plug. Remove using 14 mm box end wrench. We also used a swivel head long handled ¼” drive ratchet since we had one available, but ended up using both tools as was necessary.

İmage

Inspect removed plug. As you can see mine was still in good shape, had a nice tan color on the ceramic, but gap had opened up to .037 (as electode and ceramic wore over time). These could have been wire brushed clean, gap reset to factory spec and reinstalled. However as per my practice after 25,000 miles I went with new plugs.

İmage

With outside plug removed we had good access to the inside plug. Be sure and stuff some wadded up paper towel into the outside spark plug hole so nothing gets down in that cylinder, and again use spray nozzle to blow out any debris from spark plug cavities. Remove spark plug cap from inside plug.

İmage

A note here, if you have large hands there is not a lot of room to work on the inside plug.

İmage

Use your spark plug wrench and 14mm box wrench to loosen and remove inside plug. The Motion Pro tool has a rubber gripper inside which makes plug removal and installation easier than the factory spark plug tool.

İmage

Install the rear spark plug. Torque spec is 12 ft lbs on a spark plug. We couldn’t figure any way to get a measurement on this given the small confines of the space to work in. So we ran the plugs in until they touched then gave them a bit more, snugging them up. You certainly don’t want to over tighten them and risk stripping the threads of the spark plug hole. Reinstall rear spark plug cap.

İmage

Remove the paper towel from the outside spark plug hole, and install a plug there. Install the spark plug cap.

İmage

İmage

İmage

Move to the other side of the bike and repeat the process for that side’s two plugs

İmage

.
2014 DLX and 2006 ST 1300
"a good chunk of life's problems can be solved by going for a ride"...Guth ..... "daily" ...Ferret
10-19-2016 06:13 AM
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Rocky Offline
Road Warrior

Nova Scotia, Canada
Posts: 2,024
Joined: Apr 2014
Post: #2
RE: How To replace your Spark Plugs
You always do a great job on these tutorials ferret.
Thanks for posting Thumbs Up Thumbs Up

Still rockin', rollin', and ridin' after all these years
'67 BSA 441 VR, '70 Triumph Tiger 100, '02 Honda CB900F, '06 Triumph T100 Bonneville, '14 Honda CB1100A
10-19-2016 07:22 AM
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Pauley Offline
Running Like a Top

San Francisco Bay Area
Posts: 508
Joined: Nov 2013
Post: #3
How To replace your Spark Plugs
Awesome tutorial. Looks like a straight forward job. Thanks.
10-19-2016 07:34 AM
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LongRanger Online
Road Warrior

Evergreen, CO
Posts: 1,818
Joined: Aug 2015
Post: #4
RE: How To replace your Spark Plugs
Thanks Ferret, great job. Do you have a tutorial for changing the plugs on a F800GT? I need one!

"Happiness makes up in height for what it lacks in length." - Robert Frost
'14 Honda CB1100 DLX #000094
'13 BMW F800GT
'06 Ducati Monster 620
'98 BMW K1200RS
10-19-2016 03:32 PM
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Elipten Offline
Road Warrior

San Antonio, TX
Posts: 2,087
Joined: Nov 2013
Post: #5
How To replace your Spark Plugs
Good job. Now how about a valve check tutorial.


Sent from my iPad using Tapatalk

Current inventory

2014 CB1100 DLX
2013 CB1100
1990 BMW K75RT
10-19-2016 07:43 PM
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The ferret Online
Forum Moderator

Ohio
Posts: 18,758
Joined: Apr 2013
Post: #6
RE: How To replace your Spark Plugs
There are people on this forum capable of doing such a tute but I am not one of them. I can handle the common 90% stuff of what needs to be done to keep a bike going, but valve adjustments are beyond me.

i would hope someday, someone on this forum would do a step by step tute with pics describing that process in simple terms someone like me could follow.

.
2014 DLX and 2006 ST 1300
"a good chunk of life's problems can be solved by going for a ride"...Guth ..... "daily" ...Ferret
10-19-2016 07:53 PM
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use2b Offline
Running Like a Top

Perdido Key Florida
Posts: 640
Joined: Aug 2016
Post: #7
RE: How To replace your Spark Plugs
(10-19-2016 07:43 PM)Elipten Wrote:  Good job. Now how about a valve check tutorial.

I 2nd that .
thanks for all the effort and tips you give us , the only tip i have is don't lean closely over any power tools !!!! Thumbs Up

The best part about growing up in Florida is i didn't have to move here when i got old.
2013 CB1100AD K10
10-19-2016 08:04 PM
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Elipten Offline
Road Warrior

San Antonio, TX
Posts: 2,087
Joined: Nov 2013
Post: #8
How To replace your Spark Plugs
One day if I get to ride it enough, I will get to doing one.


Sent from my iPad using Tapatalk

Current inventory

2014 CB1100 DLX
2013 CB1100
1990 BMW K75RT
10-19-2016 08:11 PM
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Flynrider Offline
Road Warrior

Phoenix, AZ
Posts: 2,573
Joined: Apr 2013
Post: #9
RE: How To replace your Spark Plugs
Nice job, Ferret. Nice to see that tank removal isn't necessary to access the inside plugs. I also like the raised area where the plugs screw in. Better to keep any debris left in the plug well out of the hole.

Plug changing on my CB750 requires tank removal and the plug holes are flush with the bottom of the wells. I once had a tiny pebble that survived the blowing process drop into the cylinder as the plug came out. It took several hours with a telescoping rod and some chewing gum to get it out.

Phoenix, AZ
2013 CB1100 - Big Red
1993 CB750 Nighthawk - Tahitian Blue
10-19-2016 08:17 PM
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redbirds Offline
Been There

Patterson, GA, USA
Posts: 3,711
Joined: Jan 2014
Post: #10
RE: How To replace your Spark Plugs
Excellent post ferret.Thumbs Up

Philippians 4:8 (NIV)
Finally, brothers and sisters, whatever is true, whatever is noble, whatever is right, whatever is pure, whatever is lovely, whatever is admirable—if anything is excellent or praiseworthy—think about such things.
10-19-2016 08:33 PM
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