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1975BS78 carbs choke OR enricher??

Discussion in 'The Garage' started by 75XSFLORIDA, May 23, 2020 at 2:31 PM.


    75XSFLORIDA XS650 Enthusiast

    Maybe this was my whole problem. I just now installed this Choke lever. I’ve been trying to adjust the carbs without this lever and maybe that’s been my whole issue.
    OK guys is this supposed to be pushed down or clicked up when starting the bike. And I’m talking about the actual black rubber choke handle. When I say up I mean towards me....When I say down, mean towards the floor just so we’re all on the same page.
    If I start the bike when it’s UP and then click it DOWN the bike dies. How is this supposed to be? I don’t understand what actually it really is and also when you’re riding how should it be? Pushed down or up???

    Attached Files:

  2. grizld1

    grizld1 Grumpy old man Top Contributor

    When the lever is pushed down the choke valve plunger is raised, richening the mixture for starting.

    75XSFLORIDA XS650 Enthusiast

    Little off subject, let me pick your brain.....

    just took her on a 75 mph 30 mile highway ride. No issues at idle now really. After like 45 secs or so at dead stop, rpm will drop and itll pop a little and then rpm will raise back up. What could that be??

    Also when on throttle, speed continues to rise without moving throttle.... Like itll go from 30-40 with wrist staying still....any ideas??
  4. grizld1

    grizld1 Grumpy old man Top Contributor

    Your slides are lifted by vacuum operating on the diaphragm attached to each slide. The twistgrip controls the throttle plate in the carb throat. If slides are a bit sticky, what you're describing could result. If you have the OE breaker point ignition or an aftermarket electronic ignition that retains the OE mechanical advance system, the first thing I'd check would be ignition timing and function, with a close look at the advance governor (AKA "automatic timing unit"). The search function on this site works great; you'll find plenty of information on that topic.
    Greyandridin likes this.

    75XSFLORIDA XS650 Enthusiast

    Yes. OE ignition.
    I’m really not understand his bike. I just wrote it like 50-60 miles and the last 10 miles it was starting to backfire at every RPM. I played with the mixture screw a million times from a quarter to a half to a full turn it doesn’t matter. It’s doing the same thing. Everything is stock on this bike except exhaust from PO but was done 35 years ago. The only thing I’ve done is put unifoam over the stock air cages because the original foam was deteriorating.
    Help. Hating this bike more n more each day
  6. grizld1

    grizld1 Grumpy old man Top Contributor

    I already offered you help: inspect the ignition first. If you don't know how, use the search function and find out. Does the motor respond to mixture screw changes at all? If not you may have a damaged float or other fuel feed issue.
    Team Junk and Greyandridin like this.

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