'92 R100GS Carburation

Discussion in 'Airheads' started by kadesean, May 28, 2013.

  1. kadesean

    kadesean eyesuck

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    New-ish to me '92GS. Bike runs well. Changed all fluids (trans was milky), lubed the splines (good condition, but dry) and took off on a 1,000 journey loaded 2-up around Lake Huron (well most of it anyway).

    Overall fantastic trip.

    Question: 2-up with bags, 80+ mph bike doing 5,500-6,000 rpm in top gear was all I could get. Started to feel like it was running out of fuel until I backed out of the throttle. Other than that hiccup bike was flawless. I have yet to do a solo, unloaded top speed jaunt. I'm not sure that I necessarily want to change anything if I don't have to. I'm wondering if I were near normal limits or should I start 'troubleshooting'.
    #1
  2. Boxer Metal

    Boxer Metal Mad Scientist

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    Was your new-ish bike purchased some place that was at altitude? If it has 60k or so on it you might look at the carburetor diaphragms.
    #2
  3. Beater

    Beater The Bavarian Butcher

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    Had you just filled up the tank? Sometimes when there is very little 'air' in the tank the vacuum builds quickly and it can't deliver fuel as fast as it would like. Next time that happens (if ever), unscrew the refill cap to see if the problem immediately corrects itself.
    #3
  4. kadesean

    kadesean eyesuck

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    No altitude here in Michigan. The last time I had a diaphragm issue on my R90/6 it was apparent even when I was solo. I suppose an inspection is easy enough.
    #4
  5. kadesean

    kadesean eyesuck

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    Tank wasn't recently filled and it has pretty good homemade ventilation. The pulse air and shedd system have both been removed and all holes have been plugged nicely.
    #5
  6. darklight79

    darklight79 drink it , ride it , nail it

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    So how accurate is your speedo. You are right on 80 mph is about 5500 plus however might have to downshift to get more. Think yer a bit crazed to roll 2 up past 80 mph on this bike Doesnt have the brakes for it maybe breifly my speedo a good 20 mph high at 80 precison german engineering
    #6
  7. disston

    disston ShadeTreeExpert

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    1...Sounds like it might be a fuel delivery problem, clean the petcocks.

    2...And/or float adjusted to low.

    do both but my monies on #2
    #7
  8. kadesean

    kadesean eyesuck

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    Speedo was just refurbed and I believe it to be fairly accurate. I was thinking floats over diaphragms since I've experienced a torn diaphragm before and this is different. BTW: This problem happened about a quarter of a way into a 1,000 mile trip. Bike was flawless rest of the way, I wasn't on big slab afterwards
    #8
  9. supershaft

    supershaft because I can

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    The way I have seen many a GS loaded two up for a 1000 mile trip, their might be absolutely nothing wrong with your bike.
    #9
  10. akabeton

    akabeton Adventurer

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    +1

    I'm surprised you didn't get out the whip.

    2up and loaded, I don't think I'd be pushing it any further.

    Smell the roses.
    #10
  11. kadesean

    kadesean eyesuck

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    Wasn't really in a big rush. Maybe 70 miles out of 1,000 we were on the big slab. I cruised along at 70mph (the speed limit in MI), but most traffic does 75-80 so I was really just going with the flow.

    I'm going to do a high speed solo run with no bags and if she pulls right along I'm going to attribute it to not needing to go any faster loaded with bags and 2-up.

    I'm also getting used to the different gearing of the GS as compared to my R90/6. As I had mentiond the GS was around 5,500 rpm at 80-ish mph. I think at 5,500 rpm on my other airhead(s) I was traveling at a higher clip.

    BTW: Canada is cool. Props to Manitoulin Island and the Chi-Cheemaun Ferry.
    #11
  12. driggles

    driggles Adventurer

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    Recipe for a tankslapper? :eek1
    #12
  13. darklight79

    darklight79 drink it , ride it , nail it

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    A lil at 80 plus run both petcocks open for high speed go practice a high speed 50 mph stop before venturing above 80 again
    #13
  14. Dreossi

    Dreossi Adventurer

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    Check your plugs to see if you are runnig rich. Air filter clean? Check compression, might need rings or a valve job...
    #14
  15. Stagehand

    Stagehand Imperfectionist

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    to be clear: It will rev up, right? Not like it wont go above 6K's right?
    #15
  16. darklight79

    darklight79 drink it , ride it , nail it

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    airhead mag addresses this issue float levels and clean petcocks
    #16