R100GS with Bing alcohol proof floats

Discussion in 'Airheads' started by Big Bamboo, Jul 24, 2013.

  1. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    A friend brought me his 1993 R100GS with a problem. It starts and runs fine up to about 4500 rpm, but under load in top gear (passing or climbing a hill) and it starts to shake. Feels like one carb is getting starved for fuel. I pulled the bowls off to have a look see and found it had been converted to the independent black alcohol proof floats. These are not covered in any BMW manual, does anyone know the method for checking fuel levels and set up for these? Is it the same level as with stock floats, or do I need to buy a Bing manual?[​IMG]
    #1
  2. akabeton

    akabeton Adventurer

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    Sounds like your doing all the right stuff.

    Do you know any more history?

    It could be possible that more was done other than new floats. It may be jetted incorrectly.
    #2
  3. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    He bought it last year. About a month ago there was a short in the wiring under the tank, "Lots of smoke". He replaced all the burnt wires and everything works, with the exception of the neutral light, but we've narrowed that down to the switch. Ain't life a bitch! Today I found the valves were perfectly adjusted, but the carbs were way off. No free play, too much idle screw, etc. If I can't get them balanced tomorrow, I'll be pulling the diaphragms for a check.
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  4. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    No first-hand with the independent alcohol-proof floats, but general concensus is to avoid them. Snobum may have more at his website..

    --Bill
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  5. airsmith

    airsmith airhead wrench?

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    the black floats are set just like the stock white ones,,but they seem to have a little more volume to them and float better, I've had to adjust them a little past the parallel to the carb body point so the bowl fills to the correct level and the engine doesn't starve under load..
    #5
  6. Stan_R80/7

    Stan_R80/7 Beastly Gnarly

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    I've used the independent float kit since ~1990. I measure the fuel depth in the float bowls using Snowbum's website number (or I'll look the number up in a manual). Just open the petcock, fill the bowls, shut off the petcock, remove the bowl, and measure the fuel depth. It's not complicated, for me. YMMV.

    While I don't think the problem described is caused from an incorrect float setting, it is good idea to check the float levels on a recently acquired bike. The main problems I have read about with the independent floats are the plastic bowls cracking which led to the new kits having metal bowls. FWIW, the original kit plastic float bowls on mine are OK -even after carb dip cleaning.

    p.s. I bought the independent float kit because of the alcohol proof floats. Yes, gasohol existed in the 1980's and 1990's.
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  7. airsmith

    airsmith airhead wrench?

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    this is not the indepenant floats, its the one piece black float that is a direct replacement for the white floats, cost a bunch more but they don't turn into "sinks" (I ran with the indepentant floats for 20 years, bought them the first month bing advertised them) the only change is when setting the level by adjusting the tab angle you would swear by the old floats setting that fuel should be pouring out the overflow tube in the bowl, the old standby method of adjustment is start low and keep making small changes untill the starving stops.. the lack of the overflow tube in the indepentant float-bowl was their main problem, forget to close your petcocks-or leaky petcock- stuck float or bad float valve needle= cylinder filling with fuel- hit starter other cyl fires=bent rod or crank...
    #7
  8. Pokie

    Pokie Just plain Pokie.

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    At higher RPMs, fuel flow could sure be a problem. A kinked fuel hose, partly blocked tank breather,..... A little water stuck on top of the main jet mixing tube will also cause this kind of problem.

    If you have a cross over tube on the fuel line, the problem may be below that on one side. If you don't have a cross over tube, maybe you should consider adding one.
    #8
  9. Hookalatch

    Hookalatch Born Under Bad Sign

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    It seems a little complicated to me Stan. Are you supposed to do that measuring with the floats still floating in the bowl? Or do you remove them? The article doesn't say. Standard floats won't contribute to measuring the fuel depth in the standard bowl but these independent floats will. There is so much fuel that comes out of the fuel lines and cross over line when removing the bowl, which is a little fussy to get off very quickly, that I would have to somehow account for. Thought about a couple of ways to account for that extra fuel but in the end it seemed easier to just set them as Bing described.

    I have seen the warnings about lack of an overflow tube in the bowls. Perhaps I am lucky or maybe that isn't as big an issue as thought. I was riding behind a slower beat-up car a few days ago and thought I was smelling gas occasionally. I thought it was from the car. After backing off a bit I realized fuel was pouring out of my left carb. Shut the bike off and it was full flow until I turned off both petcocks. By the time I could look under the carb it was no longer leaking so I do not know where the fuel found its way out I was able to fix it roadside without even breaking out a tool. The pin the outer float rides up and down on had come lose and was holding the float against the bottom of the bowl. When I restarted the bike there wasn't any indication of richness or excessive fuel so I do not believe any fuel got past the carb. There was enough gas running out that the inlet tract should have received some even if the intake valve was closed.

    Chuck
    #9
  10. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    Yeah, I read what Snobum has to say. The lack of an overflow vent is troubling...
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  11. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    These have the metal bowls.
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  12. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    Well, I have found a couple of problems. First of all, there was water in the gas, so I drained the tank, cleaned the petcocks and am currently waiting for everything to dry out before I reassemble. Next, as I was putting the carbs back on, one of the rubber snorkels inside the airbox was dislodged. When I opened the airbox, I found the rubber snorkels had been installed on the wrong sides, with the intake pointed straight up and pressing against the air filter. The stumble on acceleration is gone, pulls like a freight train from idle all the way up to 6800 rpm. Now I'm chasing a stumble on deceleration, maybe was a bit too lean...
    #12
  13. victorlaszlo

    victorlaszlo Been here awhile

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    By there are loads of other, unknown, additives in today's fuel that very well could cause problems.
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  14. fallingoff

    fallingoff Banned

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    the additives they put in shell optimax in the 90's in oz, destroyed my fibreglass tank on my duc, took me a while to work out why the slides were sticking, dissolved resin.
    #14
  15. Mugwest

    Mugwest .

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    From 2000 edition of Bing manual

    [​IMG]

    Oh and despite the Indy bowl's lack of the old 'overflow tube' in the bowl, mine vent/puke just fine from the tiny vent hole near the choke housing area. :nod

    NB: rap on the carb body with a plastic mallet when filling a dry Indy bowl. The smaller floats like to hang up on the sides of the bowl on an initial fill.
    #15
  16. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    THANKS, good to know!
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  17. Stan_R80/7

    Stan_R80/7 Beastly Gnarly

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    FWIW, when I have cleaned up the float and float chamber (to keep with Bing terminology) as part of a 'rebuild' - some metal polish and pipe cleaners were used to clean the brass tube inserts in the floats. Having the float tubes polished keeps them from sticking on the pins. If they stick, then fuel comes out the carb vent hole as mentioned - which is aggravating. Note the bowls are not interchangeable.

    Also, in a futile effort to state the obvious, the float chamber (bowl) fuel height affects the air/fuel mixture. More height is richer and less leaner. Bing does not provide the fuel height in the float chamber but instead describes how the float arm needs to be parallel to the carb body as an indirect way to set the fuel height. I never found it easy to tell if the float arm was parallel with the carb body while installed on the bike. Apparently, that is easy for some. Again, YMMV.
    #17