Spark plugs

Nick dj

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It`s time I changed the spark plugs on my Twin Cam GS. At the last service BMW wanted to charge me a fortune for the 4 plugs.

What plugs do you use? where do you buy them

Is it worth putting in Iridium plus if so do you know which ones are for the Twin Cam.

Any advice appreciated.

Nick
 
Plugs for the TCS are much more expensive than older models I believe
How many miles have you done on the current set as they have a long life ?

Sent from my SM-G920F using Tapatalk
 
Nick V did a lot of hunting for alternate plugs and he came up with quite a list.
Standard plugs are NGK MAR8B-JDS.
He found others that fit as there is loads of room for plugs with a bigger hex than the standard 14mm.

DOHC R-series (AKA ‘Camhead’, 1 170 cm3
)
Standard spark plug
MAR8B-JDS NGK:
Can be replaced by
CR8E, CR9E
CR8EK, CR9EK
CR8EKB, CR9EKB
CR8EVX, CR9EVX
CR8EIX, CR9EIX
Denso:
IU24, IU27
 
I use Denso IU24`s in the TC, but I machine the first 2 to 3 threads off so that they resemble the stock plug.
I don`t like the idea of exposed threads in the combustion chamber causing pre-ignition and picking up carbon ready to damage the threads when they are unscrewed.
Anyone know of an iridium replacement with the same end thread form as the NGK MAR8B-JDS ?
 
Mistacat said:
I don`t like the idea of exposed threads in the combustion chamber causing pre-ignition and picking up carbon ready to damage the threads when they are unscrewed.
Click to expand...

Oh yes, i've had two bikes in where the owners thought they'd be smart and save themselves a tenner by fitting alternative plugs.

Not such a financially smart idea once you've removed both heads and had to have inserts to repair the damaged plug threads. :D
 
I got mine from the local car spares supplier. He looked up his parts list and I paid about £16 for four spark plugs.
 
Ask Steptoe. He put mine in , don't know or care what they are but sure he knows what are best.
 
NZRalphy said:
NGK iridium laser #8 are lasting and running brilliantly and are same dimensions as standard. Great plugs.
Click to expand...

I have looked at photo`s of these but they seem to have the last 2 or 3 threads in place.
Please can you tell me the part number of the NGK iridium laser 8 plugs that are a direct replacement for the NGK MAR8B-JDS with the same thread form at the electrode end of the plug ?
 
Sorry I do not Know, I have bought several sets the for my bikes and had diffs getting ones to suit. Go to eBay and type in spare-bike , they are in Slovakia, the guy was very helpful in matching and locating plugs that where not on brisk catalogue from America. Hope that helps.

Sent from my SM-J510FN using Tapatalk
 
NGK CR8EIB-10 - these are the ones I use and the electrode is still very sharp after 10000s km. All dimensions were the same as the original.
I have heard a couple of blokes using #9 plugs to eliminate the 'pinking' when using cheap fuel and apparently it improved it
 
I did the IU24 thing after loads of research.

Bike still did the stalling in traffic thing. Combined with a couple of other changes, I replaced the lambda sensors and reverted back to genuine TC plugs. Bike is now much better. Stick with original is my advice.

Sure it will probably be years before you need to shell out for plugs again, but I believe you will get exactly the same performance whilst saving only a few quid, but you will definitely get major problems which cost a fortune to diagnose if they don't work.
 
Betty Swollocks said:
I did the IU24 thing after loads of research.

Bike still did the stalling in traffic thing. Combined with a couple of other changes, I replaced the lambda sensors and reverted back to genuine TC plugs. Bike is now much better. Stick with original is my advice.

Sure it will probably be years before you need to shell out for plugs again, but I believe you will get exactly the same performance whilst saving only a few quid, but you will definitely get major problems which cost a fortune to diagnose if they don't work.
Click to expand...

Stalling in traffic/at the lights..... remove the flappy valve mate. Theory is the valve gets slow and causes the stall. I removed mine (fitted dia63mm x 70mm long tube) and no stalling. Happy days.
 
19k

I have done 19 thousand miles on the ordinals so I am sure the time has come to change them.

Has no one put the irdium plugs in ?
 
NZRalphy said:
Stalling in traffic/at the lights..... remove the flappy valve mate. Theory is the valve gets slow and causes the stall. I removed mine (fitted dia63mm x 70mm long tube) and no stalling. Happy days.
Click to expand...

If it anything like the EXUP valves used on Yamaha bikes, its worth a regular strip and clean then lubricate with a Nickel based high temperature grease. (Don't use a Copper based grease as the stuff just hardens off with heat and makes things worse.)
 
NGK MAR8B-JDS are the ones from the BMW RSD disc about £8 each online cheap enough to fit the correct recomended ones
 
Pukmeister said:
If it anything like the EXUP valves used on Yamaha bikes, its worth a regular strip and clean then lubricate with a Nickel based high temperature grease. (Don't use a Copper based grease as the stuff just hardens off with heat and makes things worse.)
Click to expand...

Unlike the Yamaha EXUP, the BMW flappy valve is all about noise reduction so it shuts on low throttle settings. It should not cause stalling but will restrict power if it sticks closed.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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