18 BMW 1973 R75/5 Install Exhaust System

I installed the top end so now I can install the header pipes I refinished and the new Sito exhaust I bought from Motobins in the UK. I bought the pipes with the “bullet end” style used with the /5 series.

You can read about how I refinished the headers here:

Parts List

Here is the parts list for this work.

Part # Description Qty
07 18 R kit 002 SS Muffler mounting bolt kit
[Hucky’s Part #]
1
88335 Sito /5 “bullet” mufflers, pair
[Motobin Part #]
1

The Invoice from Motobins which included my personal customer ID card.  That’s unique. Even with shipping, the price seemed reasonable compared to new mufflers from BMW.

Getting Started

Here is the Sito muffler pieces I received. The shipment included the two mufflers and mounting hardware for attaching mounting brackets to the muffler body.

Motobins Box with Sito Mufflers

Motobins Box with Sito Mufflers

Sito Muffler Packaging

Sito Muffler Packaging

Sito Muffler Parts

Sito Muffler Parts

I had the header nuts bead blasted. I use anti-seize on the threads in the heads to prevent thread galling.

Exhaust Header Nuts

Exhaust Header Nuts

Here is the header pipes that I cleaned up to remove the bluing and 40 years of crud. The cross-over pipe is new as the original was badly pitted from gravel. The plastic bag has the new stainless steel Allen head bolts that attach the muffler to the frame.

Exhaust Header Pipes

Exhaust Header Pipes

The headers are sealed in the head using two steel rings each with a flat and beveled side. One ring is split.

.Exhaust Header Rings, Beveled Sides

Exhaust Header Rings, Beveled Sides

Exhaust Header Rings, Flat Sides

Exhaust Header Rings, Flat Sides

Install Header Pipes

I put anti-seize on the threads of the header spigot and then put the header nuts on by hand. I check to be sure the nut goes on smoothly with no binding. This helps spread the anti-seize on the threads as well.

Exhaust Header Nut on Threaded Header Pipe

Exhaust Header Nut on Threaded Header Pipe

I put the header nut and then the steel rings on the header pipe. The split ring goes on last with the flat side facing the header. The other ring is next with the bevel side facing the bevel side of the split ring. I put a thin layer of anti-seize on the outside of the header pipe.

Orientation of Exhaust Header Seal Rings

Orientation of Exhaust Header Seal Rings

Orientation of Exhaust Header Seal Rings

Orientation of Exhaust Header Seal Rings

I insert the header pipe into the spigot in the head and push it so it is seated all the way inside the spigot. I hand tighten the header nut so there is a bit a drag on the header pipe, but I don’t tighten all the way as I need to adjust the header to align the cross-over pipe and the mufflers. I keep everything loose going from the front to the back of the bike, and then I tighten all the connections going from back to front.

Header Nut Loosely Tighened

Header Nut Loosely Tighened for Now

I install the other header pipe and then I add the cross-over pipe between them. There is a clamp that holds an Allen head bolt and a nut and washer that tighten the cross-over pipe to the stubs on the header pipe. In the picture, these are shown on the bottom, but the final orientation is on the backside of the cross-over pipe facing the engine so the the Allen head bolt and nut are protected. I keep the cross-over pipe loose enough that it turns on the header stubs so I can position the header pipes when I install the mufflers.

New Header Cross-over Pipe

New Header Cross-over Pipe

Header Cross-over Pipe Allen Head Bolt

Header Cross-over Pipe Allen Head Bolt

Install Mufflers

The bracket mounts to the muffler body. It has slots cut into it to help align the mufflers on the bike and the brackets on the frame mounts. The bracket is oriented so the slots go across the muffler body as shown here.

Mounting Muffler Bracket to Bottom of Muffler

Mounting Muffler Bracket to Bottom of Muffler

The other slots are then oriented along the muffler and allow the muffler to be moved forward or backward on the frame brackets as shown here.

Muffler Bracket Orientation For Mounting on Frame Bracket

Muffler Bracket Orientation For Mounting on Frame Bracket

The ends of the mufflers slide easily onto the header pipes. The right side has a cutout on the bottom to clear the rear brake arm. There is a bracket with Allen head bolt to tighten the muffler onto the header pipe so I don’t use the stock BMW hardware.

Muffer Cutout for Brake Pedal

Muffer Cutout for Brake Pedal

I align the muffler bracket on the frame bracket and attach it with the new stainless steel Allan head bolts. Here is view from the bottom looking up through the muffler bracket to the frame bracket. Everything lined up nicely. I tighten the stainless steel Allan head bolts through the muffler bracket securing it to the frame.

Looking Up from Bottom of Muffler Bracket to Frame Bracket

Looking Up from Bottom of Muffler Bracket to Frame Bracket

I tighten the muffler-to-header ring Allan head bolt securing the muffler to the header pipe.

Tightening Exhaust Clamp Ring to Header

Tightening Exhaust Clamp Ring to Header

Then I tighten the Allen head bolt on the cross over pipe. Last, I use the header nut wrench and tighten the header nuts. The torque setting in some manuals calls for 145-159 FOOT/pounds. But Bob Fleischer says he feels this is too tight. He, like I, use the wrench and give a good “grunt” on the end of the header nut wrench.  Bob estimates that torque is closer to 90 FOOT/pounds.

Tightening Exhaust Header Nut

Tightening Exhaust Header Nut

Final Result

Wow.  These are very nice looking exhaust pipes.  I’m very pleased with how easy they installed and how well they lined up with the existing frame brackets.

Sito Exhaust Installed

Sito Exhaust Installed

Sito Exhaust Installed

Sito Exhaust Installed

Sito Exhaust Installed

Sito Exhaust Installed

Sito Exhaust Installed

Sito Exhaust Installed

Sito Exhaust Installed

Sito Exhaust Installed

19 thoughts on “18 BMW 1973 R75/5 Install Exhaust System

  1. Pingback: 1973 R75/5 Rebuild: Install Exhaust & New Mufflers | Motorcycles & Other Musings

  2. A tip, clean all the fingerprints and grease/oil marks off the headers and exhaust just before starting for the first time as they will burn up and mark into your nice shiny surface!

    • Hi Spokenoise,

      That’s a good idea, And I assume when you daid “they will burn up …” you really meant “they will not burn up …”

      Best.
      Brook.

  3. How has the quality of the Sito exhaust held up? Thinking of going with the system over the SS. Chrome looks so much nicer. Which headers did you use and one other question what is the board on the floorjack sitting on? Not the oil pan is it?
    Joe

    • Hi Joe,

      I can’t comment on the durability of the Sito Exhaust as the bike hasn’t been on the road yet. Tomorrow is the first “ride around the block” as I will be finished with the build 🙂

      It went together and mounted with no problems so the dimensions are perfect.

      The headers are original. I cleaned them up with bluing remover. You read can about that here:
      http://brook.reams.me/bmw-motorcyle-rebuilds/1973-bmw-r755-rebuild-project/51-bmw-r755-restoring-header-pipes/

      Yes, I used a pine board and it is resting on the oil pan. The pan is ribbed and they dug into the soft pine and caused no damage to fins. There is no warping of the pan as the weight is distributed uniformly across the pan.

      If you have a way to support a BMW MC on a motorcycle jack that doesn’t require the jack being under the the oil pan, please advise how you do that.

      Best.
      Brook.

  4. I have a ’76 R75/6… Can I use a similar lift ( …just as you do, with a secured flat piece of wood) and support the bike on the oil pan…? Looks like a very practical method for servicing the bike. I’m doing a restoration/modification as well, and you’ve become a true motivation, inspiration–…and education!
    Kind regards,
    Luis M. Etchenique
    South Ponte Vedra Beach, Fla.

    • Hi Luis,

      Thanks for takikng a look at the site. I’m pleased it has been helpful.

      I’ve not had a problem with this style of Harbour Freight lift and the oil pan. I use a flat 1/2 inch think pine board just to be sure the load is spread uniformly across the entire oil pan.

      Best.
      Brook

  5. Thanks Brooke, just discovered your m/c “musings” recently, and it’s been a great learning and entertaining experience. I will surely bug you again w/ more questions.
    Kind regards,
    –Luis

    • Luis,

      You bet. I’m more than happy to tell you what I know and to refer you to those who know much more than I do. Along those lines, you may wish to join the Micapeak Airheads forum (no charge).

      —————–
      To subscribe or unsubscribe via the World Wide Web, visit
      http://micapeak.com/mailman/listinfo/airheads
      or, via email, send a message with subject or body ‘help’ to
      [email protected]
      You can reach the person managing the list at
      [email protected]
      ——————-

      It’s a nice group, a number of professionals are active along with very talented amatures and rebuilders.

      Best.
      Brook.

  6. Brooke;Thanks for all your valued info regarding upkeep of /5 bikes.
    I am original owner of a 1971/5SWB with 72,000 miles. My motometer
    speedo needle started dancing,then broke off on top of unit and under
    the glass.I I have heard that a rebuild works a bit then dies and for 400 US ,kind of risky. Been calculating speed using the rpm section. Any
    one down there have any good results or connections. Don Gervan/Canada

    • Hi Don,

      I’ve heard good things about Terry Vrla. You will find his contact information on my Restoration Resources page. There are other companies such as Palo Alto Speedometer who also offer this service.

      I hope this helps.

      Best
      Brook

  7. Brook,
    Thanks for the pics and write up.
    Did your bike not have hanger brackets that attach to the footpeg/motor mount bolts? My /5 had them and all fiche I’ve looked at had them. Left and right are different. Also looking at you pictures, the left clamp looks like it will interfere with the sidestand. Is that an illusion? Or did you have to move it?

    • Hi Brian,

      To be clear, this is not the BMW exhaust, but one made by Sito. So the brackets and other hardware are a bit different from what you will see in the BMW parts fiche.

      Yes, there were hanger brackets. There was no interference with the side stand as the tang on the side of the stand clears the bracket if it is rotated such that the bolt is not in the way. The picture doesn’t show the bracket after I adjusted it.

      I hope this helps.

      Best.
      Brook.

  8. Thank you very much for the very helpful instructions. I have a 1970 BMW R75/5 and I just got Hoske pipes and new headers from Siebenrock in Germany. May I ask you a couple of questions? Would you suggest to replace the exhaust header seal rings in any case? Or can they just be cleaned? What tires are those? Avon Roadrider? What shocks did you use in the back? IKON? What would you suggest to improve the handling of the bike?

    Thanks a lot for your help
    Best
    Marcel

    • Hi Marcel,

      Here is my advice.

      Would you suggest to replace the exhaust header seal rings in any case? Or can they just be cleaned?
      –> CLEAN AND REUSE

      What tires are those? Avon Roadrider?
      –> METZLER LASERTECH

      What shocks did you use in the back? IKON?
      –> ORIGINAL BMW SHOCKS. THEY NEED TO BE REPLACED. IKON WOULD NOT BE MY CHOICE.

      What would you suggest to improve the handling of the bike?
      ==> GOOD REAR SHOCKS. REBUILT FRONT SHOCKS. PROPER TIRE INFLATION PRESSURE. NEW STEERING HEAD BEARINGS PROPERLY ADJUSTED. THE SHORT WHEELBASE CAN CAUSE WOBBLING AT HIGHER SPEED WITH REAR PANNIERS.

      I hope that helps.

      Best.
      Brook.

      • Hi Brook

        Thanks a lot for your quick reply! It’s really appreciated. You mentioned “good rear shocks”: I live in NJ – potholes everywhere. What would be “good” rear shocks if you don’t recommend IKONs? I want to keep the look as classic as possible.

        • Marcel,

          I opted for Gazzi shocks and there are others. Hagon, IIRC, makes a shock that looks very close to the Boge shock BMW used with an optional polished shroud.

          If you want to chat about the options with a long time airhead mechanic in New Jersey, Tom Cutter, you will find how to contact him at http://www.rubberchickenracinggarage.com/.

          I hope that helps.

          Best.
          Brook.

  9. Hi Brook: Just found your website. What a treasure! The writing is clear and concise. Photography is outstanding. Just about decided to buy the Sito silencers. My question, how do they sound? Are they typical Italian, somewhat louder and healthier, or more like the originals? Not that it makes any difference, just a question. Do far, the ’71 /5 has Racetech forks, Hagon rears, Mikunis. On order is Alpha ignition from Motorad. Duralast starter. and Metzler Sports Klassic. Will send pics when done. The /5 is one of 4 Beemers and one Thruxton (air cooled). thanks again.

    • Hi Willi,

      I’m glad this material has helped you.

      The Sito’s sound very much like the the stock pipes. Perhaps a bit more rumble, but only slightly so.

      Best of success on your build. It’s great to hear another /5 will get back on the road.

      Best.
      Brook.

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