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GCCR 04-01-2013 10:30 PM

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.


GCCR

Warin 04-01-2013 10:42 PM

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

batoutoflahonda 04-02-2013 12:43 AM

check it

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

http://www.price.gmxhome.de/BMW-V2-A...p-Details.html

Plaka 04-02-2013 04:32 AM

Quote:

Originally Posted by GCCR (Post 21088400)
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.


GCCR

Talk to Carl...around here somewhere.

d mc gee 04-02-2013 07:27 AM

Quote:

Originally Posted by GCCR (Post 21088400)
Newbie here.. I shot it with PBR to break them loose. Thanks.


GCCR

PBR is a "social lubricant", it is a very poor lubricant other wise. Except the next morning.:lol3

http://dmcgee.smugmug.com/Motorcycle...ANY1263-XL.jpg

Kt-88 04-02-2013 08:48 AM

Quote:

Originally Posted by d mc gee (Post 21090119)
PBR is a "social lubricant", it is a very poor lubricant other wise. Except the next morning.:lol3

http://dmcgee.smugmug.com/Motorcycle...ANY1263-XL.jpg

Ha!

Jim Day 04-02-2013 09:29 AM

Quote:

Originally Posted by GCCR (Post 21088400)
...... 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 04-02-2013 10:20 AM

Quote:

Originally Posted by batoutoflahonda (Post 21088691)

http://www.advrider.com/forums/attac...1&d=1181056077
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.
http://www.oldkawasaki.com/image/cac...46-430x430.JPG

Or essentially like this one I just Photoshopped:
http://img11.imageshack.us/img11/3403/flangemod.jpg

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

GCCR 04-02-2013 10:59 AM

Very nicely done!:clap

GCCR 04-02-2013 11:11 AM

Quote:

Originally Posted by Warin (Post 21088443)
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!

GCCR 04-02-2013 12:06 PM

Quote:

Originally Posted by Jim Day (Post 21091098)
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.
https://sphotos-a.xx.fbcdn.net/hphot...26619935_n.jpg

https://sphotos-b.xx.fbcdn.net/hphot...57081669_n.jpg

Jim Day 04-02-2013 12:20 PM

OK.... You got me thinking, and think I may of just figured out a much cheaper and easier way to do this if there is still some threads at the cylinder.

Say you take a standard BMW finned exhaust nut.

http://store.bobsbmw.com/files/produ...1fc8712168.jpg

Then take a hacksaw and cut it completely through on one side, leaving a gap.

Find a high strength stainless steel exhaust clamp that exactly fits around the non-finned portion of the nut. There are a number of styles to choose from this type would be ideal.
http://www.himni-racing.com/images/T...let_clamps.jpg

If sized correctly this style would work as well.

https://lh5.googleusercontent.com/pu...jV8wtsU=s220-c


Take a triangular file and clean up the threads that are left at the cylinder so there are no large burs or metal that sticks out then coat it with anti-seize.

Slide your stainless clamp on the nut, slide the nut on your exhaust pipe and hand tighten it in place just like you would normally. Now you want to tighten the clamp around the nut to the point you can no longer turn in by hand, this will effectively reduce the diameter of the nut giving you the maximum thread contact. Put a wrench to the nut and tighten it just enough to get a seal, without stripping or destroying what remains of the threads. Now tighten the clamp tight around the nut to compress and lock it in place.

Once tightened in place this would hold in place mechanically the same way as Walter's solution, but you wouldn't tighten the pipes connection to the cylinder head further. It might be a little harder to get a good seal, but once you get it, it should work at a fraction of the expense.

Jim Day 04-02-2013 12:29 PM

Quote:

Originally Posted by GCCR (Post 21092320)
Hi Jim here are the pics you asked about. I'd be interested in anyone in CA that could repair this.b
https://sphotos-a.xx.fbcdn.net/hphot...26619935_n.jpg

Ouch!!! That's pretty ugly, and it doesn't look right at all. It looks like it was stripped before and someone used some kind of high temp adhesive on it to get it to hold and seal. That gray gook and stuff with bubbles in it should not be there at all, it's not aluminum.

In other words you might not of been the one that stripped it.

I'm in LA.

I have both a TIG and Mig set up for Aluminum here. I've also have access to a shop in Oxnard.
I'm not really looking for work but I'd be happy to look at it up close. If you want to bring it by I'm sure we could figure something out.

Jim

CanadaBiker 04-02-2013 01:00 PM

so I'm getting a bit freaked out by seeing these knackered threads. I'll be changing the exhaust on my new-to-me R100/7. Should I just cut the nuts off if they are the slightest bit stuck? I was planning on putting new nuts on anyway.

disston 04-02-2013 02:48 PM

You need the proper tool for removing the exhaust flange nut. When using the correct tool if it starts to feel stuck you should feel it and at that point cut the nut off. These threads are to be coated with anti-seize. Many recommend other brands. I use the Permatex, silver one.

The best repair does seem to be welding new Aluminum and then cutting new threads on the head. This is a really big thread and the die for cutting it is probably not too common. I see the die for sale on Ebay sometimes and it is a $100 I think plus shipping from Germany. I hope you can do this. Maybe there is some other way to cut new threads or the die is not uncommon like I suspect.

It does look like that head has been repaired before.

Looks of the two part flange repair aside it does work.


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