throttle settings for 1986 vf500 is mystery in the Honda factory manual

Discussion in '1st & 2nd Generation 1983-1989' started by mandolinman, Dec 17, 2010.

  1. mandolinman

    mandolinman New Member

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    After cleaning all jets, checking float levels etc I got the bike running great , and put about 200 miles on it. . The choke circuits were all cleaned and the slow jet tubes too. The bike runs great at all rpms and speeds , but after a 1 hour ride at op temp it will die at stoplight.Carbs sounded fuel starved. By moving the choke lever up about 3/8' would enable a restart, no amount of throttle would do it.
    So I pulled the carbs out, re read the Honda manual and noticed the butterflys were not set to "touch the edge of the throttle body hole" (as per the manual)....they are at least 1/64" from the edge.
    Manual says to turn the 1,2,3,4 throttle screws until they all are touching the edge. The Clymer manual never even mentions this. Is this the cause of the fuel starvation at stop?

    Any help on this appreciated.
     
  2. TOE CUTTER

    TOE CUTTER Mullet Man

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    Did you replace the boot's? Air leaks at the boots mess with gen ones at idle worse than any other.
     
  3. squirrelman

    squirrelman Member

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    What about resetting the idle speed adjustment knob ??
     
  4. mandolinman

    mandolinman New Member

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    that is good info! I never suspected these and they are kind of hard. I'll replace them and let you know but it may not be until spring!
     
  5. mandolinman

    mandolinman New Member

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    i can set it up high but it is too high to work and I could not depend on it. I will check the leaks at the boots like the other thread. I am still mystified about the edge of the bypass hole situation!
     
  6. Lazy in AZ

    Lazy in AZ New Member

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    anytime you pull the carbs for a cleaning you have to synchronize them. You can do this one of two ways. You can do a bench sync which will get them close, or get a sync tool ($100 for a decent Motion Pro) and dial them in exact.

    To do the bench sync you'll need to pull them again. DO NOT SPLIT THE CARBS. Simply adjust each butterfly to close enough to allow drag on a 1/4" wide slip of normal copy paper. Be sure that the drag is not enough to hang up the paper, but enough to slow the pull to the point that you know the butterfly is there. Do this to each of the remaining three butterflies and do your best to make them feel close to the same amount of drag. Reinstall the carbs and fire it up. Next, get a mini digital tachometer and wrap it around the #1 spark plug wire (be sure to keep it away from anything powered as it can interfere with the reading). Follow your manuals instructions and perform an idle drop on each cylinder. This is the closest you'll get to synchronizing the carbs without the Motion Pro tool.
     
  7. invisible cities

    invisible cities New Member

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  8. GreyVF750F

    GreyVF750F Member

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    Another +1 on the above. Best thing you can do is throw that Clymer manual away!
     
  9. creaky

    creaky New Member

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    +1, the Clymer is crap. I got lucky and recently scored a VF500F factory service manual on EBay, great deal for $30.
     
  10. mandolinman

    mandolinman New Member

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    Thanks this is very very helpful. OK Ill give it a shot. I can tell just by eyeballing the butterflys there is Zero clearance at not even copy paper spec there. I assume that when i do the running adjustments I am pulling the blanking covers off and adjusting the pilot screws as per the Honda Manual. right?
     
  11. Lazy in AZ

    Lazy in AZ New Member

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    Yep. Follow the manuals procedure for the idle drop and adjusting your fuel screws. If everything is done right, it should run normally afterward.

    Sounds like you've got it running lean if there is zero clearance on the plates, and that's why she is dying out without the enrichener.
     
  12. squirrelman

    squirrelman Member

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    The method that works best for me is to first align all the throttle plates so that the first progression hole appears exactly 1/2 exposed on the master carb--where the idle adjustment screw controls it-- then setting the rest the same and finally backing out the idle adjustment until only the very first sight of the hole is visible on all carbs, readjusting slightly if necessary so that all appear the same.

    I believe this is the best bench synch method, and the paper strip deal has never worked well for me.
     
  13. creaky

    creaky New Member

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    This is basically the method I used to bench sync my 500 carbs, I used a magnifying glass to better see the position of the plates in relation to the holes. After installation, a minor adjustment was needed to #2 throttle adjust screw. bike runs just fine.
     
  14. mandolinman

    mandolinman New Member

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    thanks Ill try this method too. I just set the butterflys with the paper method which proved the butterflys were completely closed and 2-3 complete screw turns to screwed to far in. Everyone on the thread was right that the carbs were running way out of adjustment,
    so I backed the screws out still not touching the hole edge but pretty close. Its a start . Now your thread gives the info to open them even more if I need to.
    I have winterized the bike so I may not be able to report results until March.
     
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