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Thread: Need starter relay for '73 R75/5

  1. #1
    DrPaul DrPaul's Avatar
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    Need starter relay for '73 R75/5

    Can anyone point me to an alternate source for a starter relay for this old airhead I just picked up? MAX BMW tells me they are backordered until sometime next summer. Thanks.
    DrPaul - 2008 K1200GT, 1973 R75/5
    2004 R1150RT - sold,1974 R90/6 - sold
    2002 R1150RT - sold,1987 K75S - sold

  2. #2
    Registered User lmo1131's Avatar
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    ALWAYS contact Rick Jones at Motorrad Elekrik for this stuff.

    http://www.motoelekt.com/chassis.htm
    "It is what you discover, after you know it all, that counts." _ John Wooden
    Lew Morris
    1973 R75/5 - original owner
    1963 Dnepr

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    Registered User jad01's Avatar
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    Quote Originally Posted by lmo1131 View Post
    ALWAYS contact Rick Jones at Motorrad Elekrik for this stuff.

    http://www.motoelekt.com/chassis.htm
    Agreed. And darn hard to beat $10 bucks. And he'll get it right the first time.
    Jim (MOA 83200)
    '78 R80/7 (Anastasia) and '84 R100RS (The Millennium Falcon), '86 K75C (Icy Hot)
    '90 and '93 Mazda Miatas (Jelly Bean and Red Hot), '97 Nissan XE PU (Mighty Mouse)
    '96 Giant Upland (big Kendas, baby!)

  5. #5
    Monza Blue 1974 R90/6
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    Quote Originally Posted by lmo1131 View Post
    ALWAYS contact Rick Jones at Motorrad Elekrik for this stuff.

    http://www.motoelekt.com/chassis.htm
    Quote Originally Posted by jad01 View Post
    Agreed. And darn hard to beat $10 bucks. And he'll get it right the first time.
    Agreed +1. I know there are a couple of sources, but ...

    Barron

  6. #6
    DrPaul DrPaul's Avatar
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    Thanks everyone. I will contact Rick.
    DrPaul - 2008 K1200GT, 1973 R75/5
    2004 R1150RT - sold,1974 R90/6 - sold
    2002 R1150RT - sold,1987 K75S - sold

  7. #7
    DrPaul DrPaul's Avatar
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    Thanks!

    Starter relay ordered from Moto Elekrik. Saved about $100 over OEM. Just finished complete overhaul of carbs; pair was mismatched (64/32/12 and /13) according to the Bing Agency, stating that /13 and /14 were the stock carbs for this model. My plan is to get it running and sort out the major systems. If no big problems are discovered will spiff her up and ride a while. The headlight bucket and chrome trim ring is knackered up a bit; looks like a PO may have had a fairing on the bike. That's about the only cosmetic issue I've found. Of course, new tires will be needed. Front brake light switch was missing and I haven't been able to locate one yet. I have a Clymer's from my R90/6 restoration a few years back. It's OK but I rely more on you guys for the best info. Thanks again!
    DrPaul - 2008 K1200GT, 1973 R75/5
    2004 R1150RT - sold,1974 R90/6 - sold
    2002 R1150RT - sold,1987 K75S - sold

  8. #8
    Airmarshal-IL James.A's Avatar
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    Dr.Paul, I'd like to offer the info that my 1973, R75/5 has 64/32/9 and 10 carburetors on it. I am the third owner and confident of the ownership history from the previous owner. That bike was sold at C&D BMW in Freeport IL., and owned in the same family until I acquired it.

    Additionally, every other 750 I have owned (/5 and/6) also had the /9 and /10 carbs.

    I once supplied a set of /11,/12 carbs from an R90/6 to a friend to put on an R75/6 that had been derelicted. His 750 ran fine with them on it.

  9. #9
    Registered User lkchris's Avatar
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    Those carb numbers just refer to the factory installed jetting, which is easily changed. There are lefts and rights, of course, but the rest is all the same.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  10. #10
    DrPaul DrPaul's Avatar
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    Update on project.

    Greetings and hope all enjoyed a pleasant Christmas holiday. Here are the tasks completed thus far:
    • Starter relay from Motorad Elektrik; works great! Thanks for the tip on this source for electrical parts.
    • Carbs chemical and ultrasonically cleaned plus completely overhauled including main jets, needles, floats and float valve seats, O-rings, seals, etc.
    • Oil pan dropped, cleaned and new gaskets installed. Fresh oil, filter. Renewed air filter and spark plugs.
    • Left side choke cable replaced (wire broken).
    • New fuel lines, filters. Petcocks work fine after good cleaning.

    Started bike for the first time yesterday and runs very good. Will need to balance carbs and check dwell/timing but I do not believe I have any major mechanical problems. Compression was 140 psi and 145 psi. Next is to service transmission and FD before test riding. Brakes seem OK but have not inspected yet. Will need tires.

    The center stand has the right leg broken off. I need a replacement. Anyone out there have one they would sell or know of a used part source? Also, the return to idle when the throttle is blipped is pretty slow. Would slide piston return springs help that? Thanks!
    DrPaul - 2008 K1200GT, 1973 R75/5
    2004 R1150RT - sold,1974 R90/6 - sold
    2002 R1150RT - sold,1987 K75S - sold

  11. #11
    Liaison 20774's Avatar
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    DrPaul -

    The forum rules don't permit trying to buy/sell items directly in the forum. But there are other options. Maybe someone will PM you with some information and you can work that off line. You can look through the Flea Market or post your own wanted-to-buy item. Of course, there is craigslist, IBMWR, etc. As for used parts sources, look into that category contained in the link in my signature line.
    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!

  12. #12
    Registered User lmo1131's Avatar
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    Carbs chemical and ultrasonically cleaned plus completely overhauled including main jets, needles, floats and float valve seats, O-rings, seals, etc.
    Did you carefully check the diaphragms for any minute holes? Did you get the butterflies back in - facing the correct direction (assuming you pulled them out to replace the o-ring on the throttle shaft(s)).

    Necessary Bing reading > http://bmwmotorcycletech.info/earlybingR75CV.htm

    butterfly reversed.jpg butterfly okay.jpg

    Also, the return to idle when the throttle is blipped is pretty slow. Would slide piston return springs help that?
    I'm not sure how you could rig a return spring on CV carbs, but synching the carbs should take care of it; at least it made a difference for me. But there are several possible suspects for a slow throttle return. You might want to consider replacing the throttle cables; doing a clean and lube on the handlebar perch; old grease and grime can make of a sluggish return. With regard to those throttle shaft(s) - I have found that a tiny dab of lithium grease on the shaft (where the o-ring rides) aids throttle return quite a bit; when compressed by the throttle shaft hole, the o-ring can add a lot of resistance to the shaft rotating freely.

    If it looks like this, disassemble and thoroughly clean every thing up. Reassemble and lube. And don't use anywhere near this amount of lubricant.



    Personally, I prefer "dry" graphite lubricants vs. "grease"; doesn't attract grit and grime. I inspect it a little more frequently, but have never experienced any problems using graphite.
    Read through this > http://www.w6rec.com/duane/bmw/control/index.htm

    "It is what you discover, after you know it all, that counts." _ John Wooden
    Lew Morris
    1973 R75/5 - original owner
    1963 Dnepr

  13. #13
    Rally Rat 1074's Avatar
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    Other stuff

    You're going in the right direction on the carbs. Yes, the slide springs will fit on the older model carbs.
    If your centerstand is in good shape other than the tang being broken off, you can fix that pretty easily. Get a piece of 1/4in. round stock from Home Depot or Lowes. Grind the area that the tang was attached to the stand (flat). Drill straight through with a 1/4in. drill. Weld both sides. Install the centerstand. With a little patience and a propane torch you can duplicate the bend going up and around the muffler. Cut the excess off, paint it and be done. Just remember that that tang is used only for dropping the stand to the ground. NOT for use when putting the bike onto the stand.
    Boxerbruce

  14. #14
    DrPaul DrPaul's Avatar
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    Quote Originally Posted by lmo1131 View Post
    Did you carefully check the diaphragms for any minute holes? Did you get the butterflies back in - facing the correct direction (assuming you pulled them out to replace the o-ring on the throttle shaft(s)).

    Necessary Bing reading > http://bmwmotorcycletech.info/earlybingR75CV.htm

    I'm not sure how you could rig a return spring on CV carbs, but synching the carbs should take care of it; at least it made a difference for me. But there are several possible suspects for a slow throttle return. You might want to consider replacing the throttle cables; doing a clean and lube on the handlebar perch; old grease and grime can make of a sluggish return. With regard to those throttle shaft(s) - I have found that a tiny dab of lithium grease on the shaft (where the o-ring rides) aids throttle return quite a bit; when compressed by the throttle shaft hole, the o-ring can add a lot of resistance to the shaft rotating freely.

    If it looks like this, disassemble and thoroughly clean every thing up. Reassemble and lube. And don't use anywhere near this amount of lubricant.

    Personally, I prefer "dry" graphite lubricants vs. "grease"; doesn't attract grit and grime. I inspect it a little more frequently, but have never experienced any problems using graphite.
    Read through this > http://www.w6rec.com/duane/bmw/control/index.htm
    Thanks for the response. And apologies to all for soliciting parts on the forum. Didn't realize that was taboo. Anyway, the diaphragms are new and butterfly plates are installed correctly. Throttle cables are by no means new but cleaned up well and are not the problem. Bowden system was a mess but that has been cleaned and re-lubed. Throttle shaft return to idle stops is brisk and complete; just takes longer than I would expect for RPMs to settle back to idle. When I ordered my carb parts from Bing Agency, I asked about slide return springs and Fay indicated they were not standard on this carb model but "could be added if necessary". I was wondering if slower response was a reason to consider doing that.
    DrPaul - 2008 K1200GT, 1973 R75/5
    2004 R1150RT - sold,1974 R90/6 - sold
    2002 R1150RT - sold,1987 K75S - sold

  15. #15
    Quote Originally Posted by DrPaul View Post
    Thanks for the response. And apologies to all for soliciting parts on the forum. Didn't realize that was taboo. Anyway, the diaphragms are new and butterfly plates are installed correctly. Throttle cables are by no means new but cleaned up well and are not the problem. Bowden system was a mess but that has been cleaned and re-lubed. Throttle shaft return to idle stops is brisk and complete; just takes longer than I would expect for RPMs to settle back to idle. When I ordered my carb parts from Bing Agency, I asked about slide return springs and Fay indicated they were not standard on this carb model but "could be added if necessary". I was wondering if slower response was a reason to consider doing that.
    You are quite accurately describing the symptoms of a sticking mechanical ignition advance mechanism.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

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