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Old 04-01-2013, 10:30 PM   #1
GCCR OP
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Stripped Exhaust Threads

Newbie here. Just started a teardown on a 82 R65. I was in the process of removing the exhaust nuts that were on pretty snug. I shot it with PBR to break them loose. But after a while, when nuts were removed I noticed the threads on the right cylinder were all but gone. Any tips on repairing them? Thanks.


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Old 04-01-2013, 10:42 PM   #2
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That is a frequent problem .. you should have cut the nuts in half - far cheaper!

See http://www.motobins.co.uk/motobins-hints-and-tips.php scan down for "Exhaust Port Nuts" for a full description.. suggest your read other bits from that site too.

It is possible to repair them ..but lots of $$$.

Google is your friend .. found http://www.advrider.com/forums/showthread.php?t=236601
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Old 04-02-2013, 12:43 AM   #3
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check it

http://www.advrider.com/forums/showthread.php?t=236601

http://www.price.gmxhome.de/BMW-V2-A...p-Details.html
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Old 04-02-2013, 10:20 AM   #4
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You have to respect the elegance and ingenuity of Walter's solution, but though I personally love it, I find his adapter to be well kinda.... Well..... ugly on the bike.

In itself off the bike it's beautiful, on the bike not so much as it doesn't match, looks small and stuck on. A 10 for it's direct simplicity and effectiveness, 6 for aesthetics as they simply do not match the aesthetics of the engine.

That said.... If I was going to go that route, I'd use his connection at the head but then I'd take the original exhaust port nut, cut the threaded portion off weld in some metal on each side between the fins and drill it to match his attachment flange.

I know everyone can't weld aluminum like I can but you should be able to find a shop that can do this.

Essentially you could still use his clamp at the head, but couple it to a finned flange that works the same way but matches the original exhaust nut configuration.

It' would be like a custom BMW version of a the old KZ Kawa exhaust clamp.


Or essentially like this one I just Photoshopped:


Easy enough to make and it would match the other side.

Jim Day screwed with this post 04-02-2013 at 11:31 AM
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Old 04-02-2013, 10:59 AM   #5
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Very nicely done!
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Old 04-02-2013, 11:11 AM   #6
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Quote:
Originally Posted by Warin View Post
That is a frequent problem .. you should have cut the nuts in half - far cheaper!

See http://www.motobins.co.uk/motobins-hints-and-tips.php scan down for "Exhaust Port Nuts" for a full description.. suggest your read other bits from that site too.

It is possible to repair them ..but lots of $$$.

Google is your friend .. found http://www.advrider.com/forums/showthread.php?t=236601
Thanks, Warin!
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Old 04-02-2013, 04:32 AM   #7
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Originally Posted by GCCR View Post
Newbie here. Just started a teardown on a 82 R65. I was in the process of removing the exhaust nuts that were on pretty snug. I shot it with PBR to break them loose. But after a while, when nuts were removed I noticed the threads on the right cylinder were all but gone. Any tips on repairing them? Thanks.


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Talk to Carl...around here somewhere.
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Old 04-04-2013, 07:18 PM   #8
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Talk to Carl...around here somewhere.
I'm still here...

Airhead cylinder head exhaust thread issues should probably have its own 'sticky' thread.

So, getting this thread back on the subject of damaged exhaust threads and not how they got to that point here is some info that was previously posted on the different types of damaged thread repairs.

For those considering the repair via cutting threads on a lathe, depending what model head you will be repairing, I expect it will take most people more than an hour to get the part set on the lathe and capable of actually cutting threads. It is one hefty piece hanging off that spindle to attempt to spin and cut threads simultaneously.

I still consider the best method to repair the threads is having the head removed form the engine, remove the damaged threads, weld and then lathe cut new threads.

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Old 04-04-2013, 08:00 PM   #9
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I still consider the best method to repair the threads is having the head removed form the engine, remove the damaged threads, wled and then lathe cut new threads.
Just curious, do you have any photos of how you load a head in a lathe? I'm still trying to wrap my head around that part. Nice looking repair.
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Old 04-04-2013, 08:24 PM   #10
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Just curious, do you have any photos of how you load a head in a lathe? I'm still trying to wrap my head around that part. Nice looking repair.
Well, based on you and I had a word sematics discussion in the past... I'll still fo go for it. I don't 'load' the head in a lathe. I attach the head to a custom fixture that threads onto the lathe spindle. Ken saw it when they were visiting us last year. The fixtures are different for the various series of heads. The R69/R69S heads require their own fixture design. Maybe some people have a 'one size fits all' fixture. I don't. Think lathe face plates and that will allow your head to wrap around all the ideas for lathe fixturing. I have fixtures for doing the welding separate from doing the lathe turning. It is crucial to have the fixture and spinning process just right or else chatter and vibration will be your worst enemy. The trick is to do some of the process manually and some under power. My latest processes used for the repairs are based on what I learned from the Maestro. One must give credit to the Maestro who so kindly took the time to allow me to review and learn his methodology.

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Old 04-04-2013, 08:34 PM   #11
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Is it some sort of expanding center that goes into the exhaust port? Do you have some sort of live center to support the back or is it just supported on the drive side?
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Old 04-02-2013, 07:27 AM   #12
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Originally Posted by GCCR View Post
Newbie here.. I shot it with PBR to break them loose. Thanks.


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PBR is a "social lubricant", it is a very poor lubricant other wise. Except the next morning.

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Old 04-02-2013, 08:48 AM   #13
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PBR is a "social lubricant", it is a very poor lubricant other wise. Except the next morning.

Ha!
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Old 04-02-2013, 09:29 AM   #14
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Originally Posted by GCCR View Post
...... when nuts were removed I noticed the threads on the right cylinder were all but gone. Any tips on repairing them?

There are a few ways to repair this. Can you post some pics so we can see how bad it is. Where are you located, are there any good metal fabricators or machine shops in your area?

Jim Day screwed with this post 04-02-2013 at 09:39 AM
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Old 04-02-2013, 12:06 PM   #15
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Originally Posted by Jim Day View Post
There are a few ways to repair this. Can you post some pics so we can see how bad it is. Where are you located, are there any good metal fabricators or machine shops in your area?
Hi Jim here are the pics you asked about. I'd be interested in anyone in CA that could repair this.


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