Author Topic: A10 Head plug thread problem  (Read 902 times)

Offline sprint

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A10 Head plug thread problem
« on: 29.04. 2014 19:42 »
Removed one of the plugs today and it came out with what would appear to be a sleeved insert attached to the plug, see photos.

It was my understanding that these types of inserts should lock to the cyl head once inserted? 

Question is what is the best way to deal with it?

The sleeve is well attached to the plug and trying to remove it will no doubt destroy the thread and make it unusable, so should I screw it back in again with some Green Loctite (or similar) and hope that will lock the insert to the cyl head or replace it with another insert?

Can you buy the inserts on their own and do you require a special tool to insert it? 

Online bsa-bill

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Re: A10 Head plug thread problem
« Reply #1 on: 29.04. 2014 19:51 »
looks like a timesert  (the ones with a flange ) , you got nothing to loose by screwing it in with some loctite and then see if the plug will comeout.
I've no experience with those type so there will probably members here who have and might have better suggestion, I have only ever used Hellicoil ( you can at least wind those out or off)

Did you by chance remove the plug with the engine hot, that might be a factor in the insert coming out
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online muskrat

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Re: A10 Head plug thread problem
« Reply #2 on: 29.04. 2014 21:28 »
Clean it well (carb clean), screw it back in use red loctite and leave it for an hour or two. The plug should then come out alone.
Cheers
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Offline trevinoz

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Re: A10 Head plug thread problem
« Reply #3 on: 29.04. 2014 22:39 »
Or the plug may become glued to the thread and the head!
I would abandon that insert and have an alternative fitted.

Trev.

Offline Clive54bsa

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Re: A10 Head plug thread problem
« Reply #4 on: 30.04. 2014 00:04 »
Hi Sprint,I had one like this on my '61 super rocket, I tried sleeve retainer several times, but eventually it would release. I always used "anti seize" lubricant on the plug. Eventually I had to pull the head and have one put in by a local machinist shop. No problem since. A pain in the rear though as i had just manage to seal my rocker box. Apparently only an issue on alloy heads.
Clive


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Online RichardL

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Re: A10 Head plug thread problem
« Reply #5 on: 30.04. 2014 00:43 »
Assuming you can't source a replacement, maybe the outer thread of the Timesert is one that you might find on a nut at the hardware store (or close). If so, buy two such nuts and cut them down so you can get two on the Timesert, forcing them together in the double-nut locking technique. With the plug in the vise and a wrench on the double nut, the Timesert should give up. I wouldn't try to say whether or not a Loctite approach would work, but it makes me itchy thinking about it. Now, Using Loctite when replacing the insert might be the right thing, but you need to know if the breakdown temperature is greater than head temperature.

Richard L.
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Online Brian

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Re: A10 Head plug thread problem
« Reply #6 on: 30.04. 2014 02:07 »
Unfortunately this is always a problem when thread repair systems are used in a situation where the bolt, or in this case a spark plug, is removed regularly.

There is a topic somewhere here on the forum that discussed this some time ago.

Back in the 70's I worked at a motorcycle shop where we used "Keenserts" a lot and always very effectively, never had one fail. Here is a clip I found on YouTube that shows how they work.

http://www.youtube.com/watch?v=XyCTh23Z6o0

In your case Sprint I think you will need the services of a specialist cylinder head shop, as your head already has had one repair it will be a bit more difficult to repair a second time.

Offline sprint

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Re: A10 Head plug thread problem
« Reply #7 on: 30.04. 2014 09:15 »
Thanks for all the replies and comments.

Plug (and insert) were removed with engine cold. I always use copper slip on the threads, so not sure as to why is has become detached?

Outside dia of insert is 16mm and has a thread pitch of 1.25, so it is a 14mm x 1.25 X 16MM X 1.25 X approx 17mm long. Anybody familiar with type of insert as to the make as getting the same insert may be the best way?

Other side has a helicoil fitted. I have the tools to do a helicoil but since the one with an insert has already been re-threaded to 16mm there is not enough meat to do a helicoil now.

See that there are some insert kits on e-bay that use a 17mm O/D insert with same pitch which may be a possibility, anybody used one of these?

 http://www.ebay.co.uk/itm/14mm-SPARK-PLUG-CYLINDER-HEAD-RETHREAD-KIT-TAP-REAMER-HELICOIL-THREAD-INSERT-/131175394133

But that means another bit more of the metal removed which I am not too keen to do.

Online chaterlea25

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Re: A10 Head plug thread problem
« Reply #8 on: 07.05. 2014 23:00 »
Hi,
Its NOT a "time sert" insert,  (these are threaded all the way and copper coated)
They are also almost impossible to remove without damaging the head (alloy)

I remember seeing a similar type insert to the one shown made by Rothenberger ???
but they had the same size tap as a helecoil or time sert

HTH
John
1961 Super Rocket
1963 RGS (ongoing)

Online bsa-bill

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Re: A10 Head plug thread problem
« Reply #9 on: 08.05. 2014 09:59 »
Dragging stuff from the basement of my ever decreasing quantity of grey matter but am I right in thinking there was  a Helicoil for mending Heliciols, sort over oversize thread, don't know, I could be way off beam, but yes it would mean removing more metal but replacing it again - is removing metal from an Alloy head an issue
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online BSA_54A10

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Re: A10 Head plug thread problem
« Reply #10 on: 08.05. 2014 10:04 »
Thread repair kits are cheap enough ans 99 of them all use the same outer thread.
The good quality ones have a pin of some sort that locks the insert into the head so it can not come out.
Cheap ones do not.
Alloy heads for A series are worth a bomb now days so it is worthwile to get it done properly.
Don't even think of reusing the one you pulled out there is a good reason why it came out.
Bike Beesa
Trevor