BMW Twin: Cylinder Head Repair

Alfonzito

Hi all,

I am currently working on a 1981 R80 BMW, a boxer twin.

When removing the exhaust nuts, I found the threads severely damaged. I probably contributed some damage myself, but most of the damage dated back to years of neglect and corrosion.

Is there a way of building up the threads again on the exhaust outlet and would anyone recommend a good engineering shop that would do this type of work.

Alfonzo

two wheels good

Alfonzito wrote: »

Hi all,

I am currently working on a 1981 R80 BMW, a boxer twin.

When removing the exhaust nuts, I found the threads severely damaged. I probably contributed some damage myself, but most of the damage dated back to years of neglect and corrosion.

Is there a way of building up the threads again on the exhaust outlet and would anyone recommend a good engineering shop that would do this type of work.

Alfonzo

I don't know of an engineering works in Ireland that will repair the stub but you'll find a few in the UK. UKGSer.com is a useful website for all things bm
The trick for removal of a seized exhaust nut is to split it with a dremel or hacksaw.

Wossack

think the usual method, is having them filled with weld, drilled and then retapped

though I personally dont know of any shops that can do so Im afraid

Alfonzito

Thanks for the replies,

I did split the nut with a dremel, but the threads on stub and nut had galled and become very brittle.

The exhaust stub is a male thread, so the stub needs to be built up on the outside and die'd. Will hopefully find someone here to do this; appreciate the market is a bigger in the UK, but would be great if an Irish firm could do this (at a reasonable cost!!). I am pricing a used cylinder head in any case.

Regards,

Alfon

MonstaMash

Alfonzito wrote: »

Hi all,

I am currently working on a 1981 R80 BMW, a boxer twin.

When removing the exhaust nuts, I found the threads severely damaged. I probably contributed some damage myself, but most of the damage dated back to years of neglect and corrosion.

Is there a way of building up the threads again on the exhaust outlet and would anyone recommend a good engineering shop that would do this type of work.

Alfonzo

Contact Leo O'Reilly, he has a vast amount of contacts in the vintage motorcycle scene, he may be able to point you in the right direction...

http://www.lor.ie/
Leo O'Reilly Motorcycles
60 Dorset Street Lower, Dublin
018307104

philgunn

Hi had the same problem a few years ago , I was able to buy the "Thread" as an insert , and then get it welded onto the cylinder head , small engineering outfit in the back of the BMW owners magazine , if you have an interest i will go looking

Phil

Alfonzito

Phil,

I would appreciate that. I managed to get a secondhand cylinderhead on the ebay on friday, but if you could locate info on the repair, I would be very grateful.

I don't like the idea of a good head being scrapped because of a stripped thread.

regards,

Alfon

philgunn

I think it was cray engineering ,
Cray engineering 01795 538282 in Sittingbourne in the UK

have a look here

http://www.ukgser.com/forums/showthread.php?224000-Exhaust-Stub-repair&highlight=cylinder+head+thread+repair

Regards

Phil Gunn

Alfonzito

Phil,

Thanks for the link and Cray Engineerings details. I have heard of Jim Cray before, he gets name checked a lot on the BMrider forum.

regards,

Alfon