spark plug inserts for twin plugs
 

I've recently had my R100GS paralever twin plugged and when I checked the new spark plugs the copper inserts on both heads came out with the plugs. I've since been sent 2 new inserts but have no thread lock glue. Does anyone know what specific thread lock to use and how to insert them?

Jem

Oh dear...

There shouldn't have been inserts in the first place!

Thread locking compound on a spark plug thread is inadequte.

Get thee to a REAL BMW Airhead expert and discuss what needs to be done with them, before your heads are irrevocably and permanently screwed up.

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Grant Johnson

Seek, and ye shall find.
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One world, Two wheels.
www.HorizonsUnlimited.com

Hello. I'm sorry, i don't have an answer for you, but i am very interested in this post. I researched dual-plugging extensively before committing and have never heard of copper inserts, only drilling and tapping the aluminium combustion chamber. I look foreward to hearing your story, hopefully it has a happy ending.

By the way, is this insert you are talking about a heli-coil?
Good luck...

Hi

I know that you can't name and shame on this bulletin board, but could you please email me with the name of the company that did the work? I'm thinking about twin-plugging and would like to know who to avoid!

Hope you get the problem sorted - there are definately people out there who have stripped and successfully repaired plug threads.

Cheers

Sean

Hi guys

This happened to me - as I've had mine twin-plugged. Whatever compound was used for the inserts didn't react well with temperature and they came out. I sent them back to Motobins who fixed them with a much better 'adhesive' and things have been fine since.

I'm not sure that the inserts are copper, though. Are you sure? they have a 'copper' apperance, but I would think it's too soft a metal for this kind of job.

I suggest you discuss with Motobins - they are ALWAYS excellent (in my experience of spending quite a lot of cash on spares over the years).

Motorworks are also excellent - so you have a choice of at least 2!

It sounds like you had a similar experience to me!

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Fuzzy Duck
(I'm quackers about bikes)

I haven't ever heard of using an insert for dual plugging - why? It sounds like somebody was correcting a mistake.....

Speaking of mistakes, here's a related one that almost caught me once.

The material on the underside of the head is thinner then where the existing plug is installed. For this reason, the second plug fitted is much shorter then the original, top plug. The shop where I had my work done failed to mention this, and I almost mixed the plugs up while doing some maintenance. It's an easy mistake if you don't know and aren't paying attention! The danger being that the longer plug in the short hole = piston contact.

Gee, what's that banging sound? A great way to get to know the inside of your engine.

Timo,

I was very interested to learn that two different reaches of plugs were needed for a twin plugged head, and I agree with you that it would be far too easy to wreck an engine by putting the wrong plugs in the wrong holes.

So, what I'm wondering is- would it be possible to use an insert (I'm not talking about the Heli-coil type of insert here) with an extended thread length to acommodate the longer-reach plug. The extra length would be on the outside of the cylinder head, naturally. I had an engine (not a bike engine) that used a phosphor bronze insert in the alloy head for the plug and these gave no problems at all, so I wouldn't expect any problems on a bike engine. I would imagine heat transfer from the plug to the head would not be a problem, phosphor bronze being a better conductor than the stainless steel Heli-coil inserts commonly used.

That make sense?

Regards,

John

John,

I suppose you could do this, but I wouldn't advise it. Again, I see no reason to use inserts, except perhaps if the existing thread has been stripped.

this would raise the head of the spark plug by quite a bit, which increases the chances of it being hit in a tip-over (remember, it's right under the head now - where the cylinder lands when you fall!). I would not want to take this risk, it has I high likelyhood of wrecking your heads, either with a failed insert or a crushed spark plug. Once you know you have plugs of two different lengths, you should be able to avoid mixing them up. I suppose if you were really worried you could get a diffenent thread size for the lower plug (when you have the machining work done), which would make it impossible to interchange them.

Don't know what gave you that idea Sean...

Feel free to name and shame, just please be sure of your facts. Fair play to ALL is important. Give the vendor a chance to correct an error, be sure it was an error and they don't have a good reason for doing something.

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Grant Johnson

Seek, and ye shall find.
------------------------

One world, Two wheels.
www.HorizonsUnlimited.com

I specified a smaller thread plug for my dual plugs. Easier to correct if there's an error made in the drilling, and if a thread is damaged along the way, simple, just drill it out a size. I'm using 10mm plugs, and can always go to 12mm, then finally 14. Spares are more compact too. http://www.horizonsunlimited.com/ubb/wink.gif

The length is always 1/2" from my experience.

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Grant Johnson

Seek, and ye shall find.
------------------------

One world, Two wheels.
www.HorizonsUnlimited.com

AGREED! The 10mm 1/2" plugs I use are nicely tucked in - a larger plug, especially on a raised insert, would easily be the first thing to hit the ground. No thanks.

Grant

I stand corrected!

Using a smaller size thread is a far better solution. Mind, I don't think that a longer plug would necessarily damage the engine in a fall, anybody who has broken the ceramic insulation of an awkwardly-situated plug while installing it can testify to that!

Humbly yours

John

Thanks for all the feedback.Just for the info the initial power and smoothness of the twin plugging was very noticable and welcomed(and that is before the timing changes).Not sure how its affected the fuel consumption yet but I'm told it'll be better.The boxer now feels closer to a Japanese 4 cylinder but just a word of warning: After recieving my heads back from the BMW workshop(no names)I realized that one of the heads was quite obviously not mine due to the fact it was covered in a grime as if it had stood for years.The best the company could do was to clean it up and check the valves.As you can imagine now I feel a little concerned that I am running a substandard part. So needless to say if you are posting of your heads just make sure you comprehensibly mark each one and go out of your way to also make sure the engineers KNOW you've done it and for what reason and hopefully you'll get yours back.Good luck Jem.