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Thread: 1971 r75/5 exhaust routing issues

  1. #1

    1971 r75/5 exhaust routing issues

    I am having an issue with exhaust fitment. On the left side of the bike I am having a problem moving the exhaust inboard enough so the gear shift doesn't hit against it when going into first. The muffler also barely clears the left shock as well. When installing the headers do they have to be seated in as far as they go or can you leave them out a little and tighten in place. Seems like a simple task but it's been a struggle for some reason.

  2. #2
    Registered User beemeruss's Avatar
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    Quote Originally Posted by gwrodzhi View Post
    The muffler also barely clears the left shock as well. Seems like a simple task but it's been a struggle for some reason.
    It may be as simple as the mufflers being installed on the wrong sides.? That would change the way they hang. Was the exhaust system removed by you and, if so, did it seem correct previously? On my '78 R80/7 the headers go all the way into the heads and that gives maximum support and sealing but I suppose that being out just a little would work. Keep us posted.

    Russ

  3. #3
    Liaison 20774's Avatar
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    Some pictures of the installation and parts might help.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  4. #4
    Not on wrong side, indentations for brake lever makes them pretty much impossible to reverse. Will try to get some pictures tomorrow. Does anyone have close up pictures of the exhaust near the foot pegs. Thanks

  5. #5
    Liaison 20774's Avatar
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    All kinds of photos here:

    http://www.bmbikes.co.uk/photopages/photosr75-5.htm

    Not sure if they have what you want.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  6. #6
    John D'oh
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    Exhaust headers must seat firmly in the exhaust spigot on the head with the split ring steel exhaust gasket against the spigot (solid ring in front). Correctly installed the crossover openings will face each other and the crossover pipe will fit in between with overlap on the header crossover outlets determined when the rear mounts are tight. The stock rear header mounting bracket marked 40 sits outboard of the foot peg mounting lug installed on the engine mount bolt and positions the header below the shift lever. The correct /5 muffler connects to the header below the shift lever and foot pegs on either side. The muffler mount flange should line up with the frame muffler hanger bracket and attach with two socket head 6mm bolts. There is a channel in the bottom of the left muffler that lines up with the rear axle. If you do not have stock BMW exhaust components for /5 short frame or correctly made after-market parts the previous info may not apply
    John D'oh

  7. #7

    New or used exhaust?

    The OP doesn't provide the origin of the exhaust system or if its a complete system or just headers, it would help greatly. If its not fitting correctly there could be a number of factors involved.

    If the exhaust came off the bike it should go right back on after cleaning it and assuming it wasn't damaged while off. If you took it apart while off the bike you have to be sure its put back on piece be piece and loosely fitted all the way to the back with the head pipes completely seated in the exhaust ports.

    If its a new aftermarket system hopefully it is a direct fit system from a reputable supplier or you may be in for a real adventure and likewise if its a used system from another bike.

  8. #8
    With most bikes, one needs to loosen up the entire exhaust system from the manifolds back, mount the silencers, and then tighten from front to back. I've had stock mufflers refuse to fit with stock headers until I loosened everything up. Not always easy with the exhaust ring nut frozen.
    '61 Clubman's Gold Star, '13 690 Duke, '13 Daytona 675R, '17 1290 GT, '18 Street Triple RS (gone but not forgotten: '76 R75/6, '84 R100, '76 R90S)

  9. #9
    Registered User lmo1131's Avatar
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    Some pictures of the installation and parts might help.
    Some pictures of the installation and parts WOULD help.

    Edit
    Does anyone have close up pictures of the exhaust near the foot pegs.
    Our friend Brook Reams has a bunch of excellent /5 exhaust shots (and others) on his blog



    You can also google, or bing, "BMW R75/5" and find a lot.
    Last edited by lmo1131; 07-26-2019 at 06:55 PM.
    "It is what you discover, after you know it all, that counts." _ John Wooden
    Lew Morris
    1973 R75/5 - original owner
    1963 Dnepr

  10. #10
    Thanks for your responses. Unfortunately I havenít had a chance to work on it. The exhaust was on the bike when I got it but removed it because it was never installed correctly to begin with. The muffler would rub at times when the suspension compressed. I will keep you guys updated once I have some time off from work.

  11. #11
    Registered User STEVENRANKIN's Avatar
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    original equipment system

    As said earlier in the thread, the owner has not mentioned if this is the original system for the bike or something a previous owner installed.

    If it is original equipment, then it should fit together with some fussing and there should be no problem.

    I have heard stories of aftermarket header pipes and mufflers not fitting properly.

    Also, pipes from another model or year bike may have been bunged in to "work" or "do the job"

    When buying or working on a bike owned by someone else, surprises can happen and they don't always happen in a good way.

    I replaced the stock headers and crossovers on my bike a couple of years ago due the fact they were rusted and cruddy looking.

    I struggled with the replacement BMW parts to get the dual cross over pipes attached on my model bike to line up and the air in the garage was blue with technical language.

    Finally I got them good enough to ride the bike over to the airhead repair shop I do business with. Glenn took about five minutes to install the system making me look like a trained monkey.

    Since you have only one crossover pipe, it should be a bit easier.

    First, assemble *on one side or the other* the cross over pipe on the main pipe and clamp it down. Slide that header pipe side into the header first. (The pipe should go in to the header till it seats.) A burr on the pipe can prevent this from happening.
    Then, insert the other header pipe. Rotate it into position to line up and slide on the the crossover pipe. Rotate the header pipes clockwise or counter clockwise until there is even spacing between both ends of the crossover pipe. Remember, the header pipes should insert all the way in to the heads till they seat.

    Once everything is even all round Tighten the clamps for the crossover then tighten the header nuts

    Glenn made it look easy because he has done it more than two times in his life. LOL.

    I don't think header pipes are marked with any kind of stamp to prove they are factory or not. I do know there have been problems with fitting Mac systems or other OM pipes.

    I hope this helped a little. If after you have installed the pipes they are still hitting the gear shift lever AND they are in fact the correct pipes for the bike, then the problem may not be the pipes but the position of the lever.

    If a previous owner was involved all bets are off as to the proper set up of the bike. I have seen somethings at the Beemer Barn that would make a person cringe. St.

  12. #12
    Thanks for all of the advice. Sorry for the delayed response but between work and some traveling haven't had much time. I got frustrated with the pipes I had so I ordered a set of keihan's. They fit as they should and all of my fitment issues went away. Needless to say I have some used headers and mufflers that some one could have real cheap.

  13. #13
    Registered User lmo1131's Avatar
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    Cool. But given the circumstances, I'm not sure why anyone would want them.. . .
    "It is what you discover, after you know it all, that counts." _ John Wooden
    Lew Morris
    1973 R75/5 - original owner
    1963 Dnepr

  14. #14
    In my experience from vintage cars, there are usually some folks with more time and skill than i. I have sold/ given away many parts that someone uses as is or modifies. Rather see it get used then go into the land fill.

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