10-19-2016, 06:13 AM
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.
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.
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.
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.
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.
A note here, if you have large hands there is not a lot of room to work on the inside plug.
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.
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.
Remove the paper towel from the outside spark plug hole, and install a plug there. Install the spark plug cap.
Move to the other side of the bike and repeat the process for that side’s two plugs
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.
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.
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.
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.
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.
A note here, if you have large hands there is not a lot of room to work on the inside plug.
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.
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.
Remove the paper towel from the outside spark plug hole, and install a plug there. Install the spark plug cap.
Move to the other side of the bike and repeat the process for that side’s two plugs
