Sorting out my R90/6 (sprouty115)

Discussion in 'Airheads' started by sprouty115, Sep 13, 2017.

  1. Disston

    Disston ShadeTreeExpert

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    I see. So are the stalks shown in you past post OEM? Or are they Enduralast also?

    If you have OEM housings then OEM short stalks should fit.

    I don't have any here to examine but I think the longer original stalks had the length in the fatter portion of the stem, not the skinny part that enters the housing. With the stalk shown and the housing mounted the skinny part will will show and I don't think that is correct.

    Maybe used parts at this place in your endeavors would work better than aftermarket. The short stalks and original housings are fairly cheap used. S fairing longer stalks are very expensive. Very. Like sometimes around a $100 each.
  2. sprouty115

    sprouty115 Long timer Supporter

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    Yes, the stalks are OEM that I ordered from Ebay. The turn signals are Enduralast.

    Interestingly, Euro MotoElectrics also sells stalks, but only the long version. So I guess they're meant to work together. In fact I would have ordered the stalks from them, but they were $54 each and I happened to find the set on Ebay for $40 pair...just didn't realize they were different lengths.
  3. Disston

    Disston ShadeTreeExpert

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    So now you need original housings?

    I don't know what would work and cost you less. These problems are run into all the time when using aftermarket parts.
  4. sprouty115

    sprouty115 Long timer Supporter

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    Since the last post I've been out riding as much as possible and the bike has been running pretty well and I'm really enjoying it.

    It starts almost instantly, and now requires the choke (before it wouldn't start with the choke on at all). It takes a few miles to warm up, but I believe this is normal. I do however, have a slight hesitation as soon as the throttle rolls off idle. I've made small adjustments to the idle mix screws, idle stop screws and the cable adjusters, but I can only make it slightly less bad, and not completely gone. I've been at this awhile now and I feel like I have the basics covered (timing, valve clearance, fuel bowl height, etc,) but I'm not quite there yet. I did get a set of shorting sticks and will see if I can figure anything out trying to balance the carbs that way...




    In the meantime, I'm looking for a new seat (stock looking) - the foam on mine is shot and the trim has been replaced with an aluminum trim piece that looks a bit "off".

    So I've done a few searches, but I'm not seeing a definitive consensus. Anyone have an opinion? Other options besides what I have listed below?

    OEM - $650
    https://shop.maxbmw.com/fiche/DiagramsMain.aspx?vid=51889&rnd=07242017

    Wunderlich - $500/$550+
    http://www.wunderlichamerica.com/motorcycle/5253961.html
    http://www.wunderlichamerica.com/motorcycle/5255600.html

    Sargent - $350+
    http://www.sargentcycle.com/Seats-Accessories/BMW-Classic-Skins-Complete-Seats/VCA-966.html

    S. Meyer - $270
    https://www.meyer-bikes.de/index.php?page=details&art=52531233960b

    Mayer and Corbin are out - can't get past the non-stock look...
  5. Plaka

    Plaka Brevis illi vita est

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    a stumble off idle means the transfer ports in the carb are clogged. These are two very tiny holes in the bottom of the venturi just in front of the butterfly. If you pull the idle jet and spray some carb cleaner in the idle jet hole you should see some come out of the transfer ports. More carb cleaner may clear them or a poke with a very fine wire. You may need to put a finger over the big idle port in the venturi to get some pressure at the transfer ports.
    Bigger Al, Jim K in PA and sprouty115 like this.
  6. sprouty115

    sprouty115 Long timer Supporter

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    Thanks, I'll be on that this weekend!
  7. Jim K in PA

    Jim K in PA Long timer

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    Motobins in the U.K. Has a pretty good selection. I've bought several seats from them, including a couple of their "pattern" replicas. I think the S. Meyer seats are what 'bins sells.
  8. sprouty115

    sprouty115 Long timer Supporter

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    Was leaning towards Meyer or Sargent. Thanks for the input.
  9. nobbylon

    nobbylon Long timer

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  10. sprouty115

    sprouty115 Long timer Supporter

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    Looks like the same seat as the Wunderlich link? Sort of wondering what the extra money buys me?
  11. nobbylon

    nobbylon Long timer

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    Yes I think they are the same. I’d ring meyer and ask them to send you a pic of the underside of their seat.
  12. Plaka

    Plaka Brevis illi vita est

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    While you're having fun, remove both idle air adjuster screws. Do not lose the springs. These screws have a very fine tip. It isn't conical; sort of an ogive tit. If someone has mashed one down the tip may be distorted or broken off. If found, replace the screw. examine the "seat" as well. The tip should never contact the seat. A missing spring is no good. Replace it.

    The o-ring on the idle air screw is the same one as on the idle jet. But the one on the jet runs in a taper bore and seals down. The idle air screw o-ring runs in a cylindrical bore. I only get about 2 years out of that one. Always good to have spares on tune-up day. The symptom of a bad idle air o-ring is that when you turn the screw, nothing happens. The o-ring may look good but when you go to take it off you see the cracks.

    Your o-ring pick should have a well blunted end to prevent scratching the brass.
  13. PaulBarton

    PaulBarton Been here awhile Supporter

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    . Great use of the word! Are you an architect?
  14. Plaka

    Plaka Brevis illi vita est

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    no, an admirer of women.
  15. sprouty115

    sprouty115 Long timer Supporter

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    Thanks for the suggestions. I rebuilt the carbs at the start, and I actually replaced at least one if not both idle screws (need to see what I ordered?), and all the orings, but it never hurts to check.
  16. Disston

    Disston ShadeTreeExpert

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    I didn't come up with this idea myself but I forget where I got it from.

    When doing Bing carbs and sometimes other things that are used in pairs on our bikes I always replace both items in each carb if one is bad. Say I need a diaphragm because one has a pin hole? I replace both because the other one is just as old as the one that failed. Maybe I could get by with only doing one but more likely I think the other one will go out pretty soon.

    Other things that I have encountered included an idle mix screw I had that had a bent tip. No idea how that happened. It was years ago and the bike came that way to me. Now the other carb had a good idle mix screw but the advice was to replace them both because these parts sometimes have design changes and manufacturing tolerence's and a new screw may be slightly different from the one that is 40 some years old.

    I know this borders on being too anal but I feel better sometimes trying to keep things balanced.
    sprouty115 likes this.
  17. Plaka

    Plaka Brevis illi vita est

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    mmmm...sounds thorough. The only gotcha is subtly slicing an o-ring when installing it and not noticing. But you don't cite any symptoms consistent with that.

    When checking the height of the fuel in the bowls you want to measure down from the top. It's easier. WHat matters is the height of the fuel over the main jet. The height of the fuel in the bowl is a surrogate for that. But what you can do is pull the bowl and hold a jelly glass up to the bottom of the carb. The glass should be small enough to engage the bottom of the carb body and big enough to allow the float to move freely. Then just turn on the gas. Mark the height of the gas on the outside of the glass with a fine tip marker, dump the gas back into the tank and do the other side. This won't give the same reading as the height in the bowl (the glass won't go up into the bowl groove) but it makes it a snap to check for evenness side to side.

    The standing brass tube in the carb bowl is not a vent, those are up in the carb body. It is an overflow.
    sprouty115 and Jim K in PA like this.
  18. Plaka

    Plaka Brevis illi vita est

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    You flunk being a poverty rider. PRs use things up...all the way. I was once following Matt on a long trip east. It's raining a bit and suddenly he pulls onto the shoulder with the bike stumbling. He diagnosed it by goosing the throttle a few times without stopping then limped along the shoulder to a rest area. Once under cover he changed out a diaphragm in about 5 minutes. He just did the one but I noticed he was carrying 2.

    Since then when I do a major service I make sure all the screws to change a diaphragm are free with fresh anti-sieze.
    Jim K in PA and Bigger Al like this.
  19. Disston

    Disston ShadeTreeExpert

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    I do seem to have my own version of difficulties Plaka. And to be honest I think the PRs have better running bikes sometimes.
    Jim K in PA likes this.
  20. Jim K in PA

    Jim K in PA Long timer

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    Clever. :thumb