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Full throttle = bike chokes mono r80 bmw

Discussion in 'Old's Cool' started by Uncle Pollo, Feb 14, 2011.

  1. Uncle Pollo

    Uncle Pollo Long timer

    Jun 1, 2006
    Albuquerque, Neue Messico
    The bike runs fine going on slower speeds, open throttle full at highway speeds and the bike "chokes" (like it is not sucking gas), then back off a bit and it is allright. It bothers me because I don't know what it is, it is not a safety problem (au contraire, it prevents me from running the ton every day) but I want to fix it!
  2. Sniper X

    Sniper X De Oppresso Liber

    Jul 18, 2006
    Central New Mexico, 7420ft above sea level
    I still think there are pinholes in the diaphrams....lets throw a set of mikunis on that thing!
  3. Dolly Sod

    Dolly Sod Red Clay Halo

    Aug 18, 2003
    Richmond, Va
    My first guess would be holes in the carb diaphragms.

    Also fuel flow restriction, or leaky float bowl gaskets sucking air. Improper float height. Maybe the spring on the floats is sticking, keeping things too lean in the bowls.

    Also could be weak spark breaking down under full load. charging system OK? Battery Good? Ignition switch in good working order? I had one that would miss under full load because the ignition switch was going bad the the extra vibration would cause an intermittent miss as the contacts arc'd.

    Why not throw a carb kit at it? You get diaphragms with BMW kits so you can eliminate that possible issue, and verify that everything is clean and well sealed in the carb.
  4. bpeckm

    bpeckm Grin!

    Apr 2, 2008
    Road Island
    The primo suspecto would be fuel delivery, a classic case of fuel starvation when fuel is most needed...

    As above, check float levels, check fuel flow from each petcock. Both easy checks, and likely to be the problem... if not, then go for the diaphragms.

  5. lkchris

    lkchris Albuquerque

    Feb 23, 2005
    Make that "secondary," as clearly diaphragms are first.

    Cracking the throttle open does nothing directly in terms of fuel flow, but it sure does want to cause the diaphragms to raise the needle jets.