Installing a new exhaust system

[robbob100s]

Oh wise ones, I need some advice on putting on the new headers and mufflers on a ‘77 R100S. I know that there are tricks to the job so that it goes easier, just can’t remember them, lol. I know that I don’t want to stress the threads on the heads. Front to back? Loose then tighten? Thanks Robert

[barryg]

Put a lttle antiseize on the threaded aluminum exhaust nut to keep the threads from galling up on the threads of the exhaust port of the heads.

[Bob_M]

On the Epco muffs I installed there is a right and a left. They look almost the same if you put them on upside down on the wrong side, but they will conflict with the bags.

DAMHIK

[108625]

Don't tighten anything up until you have everything together.

[danielroth]

you will have to replace the fishfood gaskets. be very careful fitting the pipes together not to damage these. use of an exhaust pipe expanding tool is advisable.

use a rubber mallet on the header to be sure its seated fully in the exhaust port then hand tighten the exhaust nut. use of a hammer anyplace else is usually a bad idea meaning some component is not where it should be.

leave it all loose until the whole thing is hung. all the pipes should be perfectly lined up before you tighten clamps.

defiantly anti seize on all threads. also, note: never try to loosen hot exhaust nuts.

the main point is care should be taken that the exhaust is perfectly aligned and leak free. max fritz would have it no other way.

[James.A]

Don't tighten anything up until you have everything together.
I think that Bob from Montana has it exactly right. All I would offer is that once you have it all "hung loose", tighten from the front to the back.

[jamesdunn]

Be careful when attempting removal of exhaust nuts, that is , if you've not already removed them. Don't force them. You may "wreck" your heads. They may be "frozen" and will need too be cut off with a Dremel tool or similiar. Then replaced. You can try penetrating oil first. I have read Kroil is a superior product. Apply anti-seize when reinstalling and loosen from time to time and re-use.

[James.A]

Be careful when attempting removal of exhaust nuts, that is , if you've not already removed them. Don't force them. You may "wreck" your heads. They may be "frozen" and will need too be cut off with a Dremel tool or similiar. Then replaced. You can try penetrating oil first. I have read Kroil is a superior product. Apply anti-seize when reinstalling and loosen from time to time and re-use.
It is one of those things that many of us "know" but it is always a good thing to be reminded of.

[GlobalRider]

Be careful when attempting removal of exhaust nuts, that is , if you've not already removed them. Don't force them. You may "wreck" your heads. They may be "frozen" and will need to be cut off with a Dremel tool or similiar. Then replaced. You can try penetrating oil first. I have read Kroil is a superior product. Apply anti-seize when reinstalling and loosen from time to time and re-use.

If they have been on for a long time and through all kinds of weather, I'd cut them off and not even take the chance of damaging the exhaust stub threads on the heads. Not taking your time here can cost you hours tomorrow.

A new set of finned exhaust nuts should be on hand so that you can measure how deep you can cut into them till you reach the major diameter of the threads. Then back off that dimension by 1 mm.

When using a Dremel with a cut-off blade...wear eye protection!

Place two cuts front to back 180° apart. A chisel blow should be enough to snap or enlarge the nut to lossen it.

Once off, the exhaust stub threads on the cyclinder head should be throroughly cleaned.

Use liberal amounts of anti-seize on the new nuts and on the exhaust stubs, then wipe of the excess.

I've never had to take those steps due to regular exhaust stub maintenance...

BMW Airhead Exhaust Stub Care (http://edelweiss.smugmug.com/gallery/4540675_awrLm#267458392_6zhF7)

:wave

[sumran]

I used the proper tool to take the nuts off and they came off without a problem after helping the tool with light taps of a rubber mallet on the handle.
The bike has sat for 10 years!

Is the exhaust on the 77 R100S that you are installing a 38 or 40mm?

Glad yours worked out. They were probably given a good coat of anti-seize when last put on. The distance between "I think I can get it loose" and "My threads are ruined" is pretty short.

If it does go badly there was a new item shown in a recent Airmail issue that replaces the factory system of attachment without rethreading the heads. Not as attractive as the original but functional and much less expensive.

[robbob100s]

The inside of the pipe is 37.87mm or 38mm.
Thanks for the help everyone! The nuts came off ok, sort of, I will clean they up and take some pixs. The right side has some, I fear may have been damaged before.......
Robert

[robbob100s]

I like to get my hands on the P.O.!!

[tghsmith]

from the pic it looks likes you still have enough there to be workable, start at the good tread area and work forward with small files clearing out the threads so a new nut will spin on, lots of antisieze and a little luck everything should workout...

[GlobalRider]

I like to get my hands on the P.O.!!

I've always said, there are butchers, there are mechanics and then there are craftsmen.

[PHMarvin]

Hi, Robert,
The spigots can be repaired, if necessary. One place attaches a new spigot to the head (NOT recommended) while the others weld new material to the head and then recut the threads. In my dotage, I've forgotten who actually does the repairs, but Tom Cutter, Oak, Matt Parkhhouse, Ted Porter, Bob Clement, etc. can, I'm sure, be of help if this repair is necessary.