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Ninja EX500 carbs on an XS650?

Discussion in 'The Garage' started by Highside, Oct 20, 2011.

  1. I dunno if the synch linkage would work correctly with a downward-pointing screw - hadn't thought of that. I guess another idea would be to replace the stock synch screw with a hex head or Allen one a couple inches longer (if such screws even exist - I haven't looked). Whether pointed up or down, it seems like that would put the point of contact for the right wrench in a more accessible spot than the stock screw. Either way, this mod should happen with the carbs off the bike, so a careful bench synch could be done first. I'm not familiar with how these carbs are accessed on EX500's/GPZ500's - must be open access from above after removing the seat or some piece of bodywork. I hadn't even thought about how to access the stock synch screw before installing these carbs on my 650 - it starts and runs well, but I'd like to be able to dial in the synch really tight to minimize vibration. One of these days, gggGary is gonna try these carbs - maybe he could give this some thought aforehand. So far, the only downside to this mod that I've found is the "between the carbs" throttle cable and synch screw access.
  2. yes I wasn't really aware of this before buying them but I'm sure there will be a way of modifying the throttles to accept an external adjust screw I'll take a look at them when I get back off holiday.
    The sync screw will work fine with the screw pointing either way.
  3. No need to extend or do anything to the sync screw..........they will be bench sync'd before installing so any adjustment should be miner to say the least, if needed at all..........Buy an offset screwdriver........problem solved............

    In fact the BS38's and 34's are just as problematic to adjust once they are on the bike, and any sync work done after the carbs are fitted would involve taking the tank off in most cases..........Non issue in my book

    , offset screwdriver.jpg
    Last edited: Sep 12, 2017
  4. Thanx for your suggestion. The first thing I tried was my trusty 55-year old offset screwdriver; it had maybe 15 degrees of "swing", not enough to even engage the screw, let alone turn it a bit. Never had BS38's but ran 34's for about 6 years before updating to CVK's. I did synch the 34's on the bike but probably had the tank off the times I did it. Agree that any adjustment should be minor after a good bench synch. In my experience and opinion, it's still worth checking and fine trimming if possible - synching any carbs within an RCH on these 650's is the best single thing you can do to minimize vibration, plus it accounts for any other factors beyond the carbs that may affect strength of vacuum on one side or the other.
    peanut likes this.
  5. found that pic with the extension for the idle adjustment
    ex   500.JPG
  6. personally, i can't say as to these carbs needing a final sync after a bench sync. I'm sure it is the sound thing to do, just for knowing/final tuning.

    looking at the EX carb diaphragms and comparing them to BS38's/34's the EX diaphragms look to be stable.........all the factory XScarbs i have seen, the diaphragms look tired and the bowl shape of the diaphragm is all twisted............could also be an age factor.........my EX cabs are NOS.

    i'll do some shot comparisons and post up the pics
  7. Yeah, that's the one referenced in post #880, used on 2000-2001 Kaw W650's per the carb fiche for that bike. The fiche doesn't show any other applications, so likely a pretty rare as a salvage item.
  8. You'll find that you won't need the "push" cable and can safely trim off its tab if you want to "declutter" - return spring on these carb sets is quite strong.

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