cylinder head exhaust port problem

[mtpica]

I've got an 1984 R65 that has had the threading on a cylinder head exhaust port completely machined away.  

A steel collar with external threads to match the exhuast "nut" was pressed onto the now threadless exhuast port.  It was probably a tight fit when it was first done, but now the steel collar freely slides on and off of the head's exhuast port making it virtually impossible to tighten up the exhuast nut.

Any thoughts on how to fix this "right"?  A local machine shop suggested I just thread the nut onto the collar and get it as tight as I can.

thanks!

Mark
portland, or

[Justin B.]

I think there are some specialists that will actually weld a new stub on for you, hopefully somebody here will chime in with who they are.

[thrang]

If you're in the UK both Motorworks and Motobins can put you in contact, otherwise a post on the Yahoo IBMW mailing list should be able to point you in the right direction.... But it probably won't be cheep and might be worth just sourcing a second hand head.

[Mumford]

Might want to give Bob's BMW in MD a call. They offer a pretty decent range of services, and seem Very familiar with Airheads. Assuming I can save the money, they're getting my heads this winter. . . http://www.bobsbmw.com/service/components.html

[Justin B.]

Also, Bruno's comes highly recommended and I think Sue has had dealings with him.  I was going to send my heads to him to be redone but he was in the middle of moving at the time so I was able to find someone locally.

http://www.brunos.us/

[Rob Valdez 79 R65]

Call Bob Grauer, and see if he will do it for you.  Excellent work.

rgrauer@earthlink.net  408 248 9732

He is in San Francisco.

There should be someone in the Seattle area.

[mtpica]

thanks folks!  I'll check with the west coast options first.  

As an FYI, a local rider also recommended:

Ted Porter
Scotts Valley, Ca.
831-438-1100
www.Beemershop.com

Mark
84 R65
82 R100RT

[Justin B.]

Probably any mentioned here will do you a good job.  Is it possible that the pin "fell out"?  I would think that a press-fit exhaust spigot would have some sort of tapered pin driven in to keep this from happening.  You might want to run what you have by a general machine shop and get their opinion.  If this is the only thing wrong a good machinist might be able to fix you up quickly and inexpensively.  But, if you are going to spring for a valve then it may be best to visit a specialist...