BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: Steve Tipper on 30 November, 2017, 14:09:20

Title: A65 extreme spark plug thread repair
Post by: Steve Tipper on 30 November, 2017, 14:09:20
I've just got hold of the correct OIF type head for my A65 project.
One of the plug threads has been butchered by a drunken gorilla.
A standard helicoil just isn't going to be possible.
By the look of things either the hole is going to have to be completely welded up and re-machined or some sort of substantial insert fitted.
Any recommendations please ?

Title: Re: A65 extreme spark plug thread repair
Post by: Steve Tipper on 30 November, 2017, 14:30:36
Photos
Title: Re: A65 extreme spark plug thread repair
Post by: Bess on 30 November, 2017, 14:42:37
Hi,
    By the look of the images, I would source another or send to SRM in Wales, they give an estimate and recommendations before starting.

Best wishes...
Title: Re: A65 extreme spark plug thread repair
Post by: A10 JWO on 30 November, 2017, 16:24:25
I had similar issues with a Ducati head years ago. I took it to a vintage car restorer, the head was heated to the correct temperature, welded and a new thread cut. Get a copy of Old Bike Mart, there are loads of engineering adverts in there. Otherwise have a run around your local trading estates and find an establish old school workshop, there are loads out there; you will be surprised and the old lads enjoy these challenges. They generally don't take liberties.
Title: Re: A65 extreme spark plug thread repair
Post by: om15 on 30 November, 2017, 16:43:56
I had similar and had it repaired here

 http://www.g-c-s-motorcycles.co.uk/

Good job, good price and had a tour of the workshop, nice bloke owns it,
Title: Re: A65 extreme spark plug thread repair
Post by: Cyclops on 02 December, 2017, 18:32:24
Hi, have just had some work done on a S/Rocket head, one of the repairs was on a thread insert fitted incorrectly. Whilst there, the cyl. head guy (40 years experience) showed me the 3 types of insert, call them stage1,2 and 3. Stage 1 is a helicoil for cross/stripped plug threads. Stage 2 is a copper coated medium steel insert for use where there is insufficient metal to accept a helicoil. Stage 3 is a heavy duty copper coated steel insert for totally butchered holes. These have to be fitted by an skilled engineer. mine wasn't and came out attached to the plug whilst removing it for inspection. This was remedied by using a special loctite. They told me if the insert ever needed to be removed, it would have to be machined out, it's that good. Don't know your location, but the firm i used was South Cerney Engineering Ltd, Ashton Keynes near Cirencester. Worth checking out their website.
Title: Re: A65 extreme spark plug thread repair
Post by: Steve Tipper on 02 December, 2017, 19:13:12
Thanks for all the advice.
It looks like a stage 3 job to me.
I think that I know of an engineers in the Midlands who may be able to help me out with this.
If they can't they will be able to point me in the direction of somewhere that can.
I think I'll have to get a small amount of weld added around the outside face before machining starts.