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Gas in oil and puking

Discussion in 'The Garage' started by SeaJay, Oct 17, 2020.

  1. SeaJay

    SeaJay XS650 Member

    Let me start by saying I’m not a bike guy. I’ve been building cars since I was 14, but I’ve never built a bike and I’m really just learning them since I picked this one up. It’s a 78 XS650. Yesterday I was on a ride and ran low on gas, when I switched the petcock to reserve it dumped fuel in the crank case and puked the fuel/oil mixture all over the place.

    Do I just have a petcock problem? They’re leaking around the base, so I was going to pull them off anyway, but shouldnreplacing then take care of this problem?
    gggGary likes this.
  2. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Good chance you dumped a bunch of crap from the bottom of the gas tank into the carbs. so redo those and an oil change... would be my guess.
    SeaJay and bikefreakjon like this.
  3. Machine

    Machine Race the wind Top Contributor

    78's should have both properly functioning vacuum petcocks and or properly functioning carburetor needle / seats which stop the fuel flow.
    On centerstand with say a 2×4 under the front wheel, the carburetors are at such a more level angle that fuel over flow will spill out the air filter side instead of worse, forward into the engine intake tract.
    It is a good idea to test the function of the petcocks with the bowl drains out. I actually store my 78/79 series with the drains out ensuring function. (Pan under carbs for ovservation)
    Storing BS38'S dry seems like a good idea as well. Then simply "prime" the carbs. That also cleans the lines, needle/seat, and bowls.
    Good To Go :thumbsup:

    Attached Files:

    gggGary likes this.
  4. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    +1 on what Gary said. Also flush out the tank and repair the leaking petcocks.
    gggGary likes this.
  5. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Pics too small to tell if the petcocks are original vacuum or replacement manual type.
    Machine likes this.
  6. SeaJay

    SeaJay XS650 Member

    I don’t post any pics, but I will. This bike appears to be comprised of parts from 72-78. Frame says it’s a 78, title says 72.
    gggGary likes this.
  7. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

  8. SeaJay

    SeaJay XS650 Member

    gggGary likes this.
  9. SeaJay

    SeaJay XS650 Member

    These are not the vacuum ones, correct?

    Why do these petcock not have an off position?
  10. SEd27

    SEd27 XS650 Enthusiast

    SeaJay likes this.
  11. SeaJay

    SeaJay XS650 Member

    Theres no vacuum line run to them.

    I would prefer to just replace them. If I do have the vacuum type I can just replace them with manual ones with no issues?
  12. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Well they were vacuum at one point in their life.
    I'm gonna say it.
    You are going to have a bit of winnowing sorting to do on this one. She's a looker but as is often the case, high maintenance comes along for the ride.
    Couple things point at corner cutting.
    Those petcocks not hooked to vacuum
    fake pod filters gotta go LOL.
    No fuel hose clamps.
    I'd want to open those carbs and check what brass, jets are in them.
    I'm not too fond of those plastic fuel filters.
    Hope I'm not popping any bubbles, cuz it looks pretty cool.
    Paul Sutton, SeaJay and grizld1 like this.
  13. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Many aftermarket petcocks have a somewhat spotty reputation.
    grizld1 likes this.
  14. grizld1

    grizld1 Grumpy old man Top Contributor

    Yeah, they're vacuum petcocks, there's no "Prime" setting on a manual unit (and no need for one). Be aware that OE manual petcocks mount on 42 mm. centers, and your tank requires petcocks with holes 46 mm. apart. Word to the wise: click the "Tech" button and find out where to download a factory manual, and back it up with a Clymer's manual and some searches.
    Paul Sutton, SeaJay and gggGary like this.
  15. 5twins

    5twins XS650 Guru Top Contributor

    There used to be a method of converting the vacuum to manual petcocks outlined on the 650Wiki site but it appears that site is gone now. But, maybe that was done to yours a while back while the instructions were still available. From what I recall, it involved swapping the petcock arms side to side and somehow jamming the spring-loaded vacuum operated plunger on the back in the closed position.
    SeaJay and gggGary like this.
  16. SeaJay

    SeaJay XS650 Member

    No, not popping any bubbles at all. I’m here to learn. Like I said, I’ve building cars for 25 years and I want to learn bikes, or at least this bike. The bike is exactly as I bought it except I had new tires put on and powder coated the wheels when that was done. It was a show winner at some point in its life, but that was many miles and many repairs ago. My intention in buying it was to enjoy it and slowly go over it nut and bolt to get it back in pristine condition. So the things you’re saying are the exact kinds of things I want to know. Otherwise, I’m kinda lost. The only bubble being popped around here is the giant bondo one on my gas tank...
    Paul Sutton and gggGary like this.
  17. Jan_P

    Jan_P XS650 Addict

    Some Thoughts
    I am not an "Carburetor " man and don't know if the bike has been parked. for longer time
    So if no vacuum line the bike has been running in an open position.
    And on my 1980 there is such a position pri
    others are on and res
    So the petcock has been open before but not in the res position.
    The float valves stop the flow so it does not need to be a big problem

    I once modified a stock petcock .. And removed the handle with front
    and put an aluminum plug with some
    hard loctite .. Cant exactly remember how I did but had i so for several years
    At least five.

    What has happened I believe is that dirt ( rust ? ) at the lower level from the tank .
    Has come down and the float valve does not close.
    That can happen fex at startup in the spring. but stops after a short time.
    Have also happened out on the road one time . ( The girl passenger looked Nervous )
    It drips right under the carburetor that have a hanged float
    I tap gently on the outside of the float bowls. with a screwdriver handle och wooden hammer handle
    Trying to get it moving.
    I am not sure the meaning of getting into the oil so but that is of course not good.
    With a vacuum operated petcock i the flow stops with stopped engine
    But since you don't have that the tank content can run through .

    If this was me I would take off the tank and flush it ..getting dirt out
    The tap removed ( perhaps a gas filter is needed )
    Then I would inspect the tap ,And install perhaps a new gasket
    There are kits
    Something like that please google better

    One can open the float bowls from under with the right tools and
    flush and try to clean but I would not do that .Directly ( A bit Red neck Service )
    I would then put a clamp or something on the fuel line so I can stop the flow
    If the gas runs through.
    Starting it and revving up and down --- clamp and open so the float moves inside.
    I think there is a good chance it starts moving.
    There is of course the risk that you have dirt inside the carburetors and the bike can stop
    But I have had virtually no problems with carburetors over the years .
    I believe those are fairly forgiving .. I have had leaking Air filters.
    But on some bikes there are no filters.
    Take it for what it is worth.
    Removing carburetors and do a full service is at times needed.
    But a typical winter job .Some times the quick fix and getting it running is a better way forward.
    It might not run as well but life is full of Compromises.
    I don't think I ever have used the res Position. Filling up after shorter distances.
  18. SeaJay

    SeaJay XS650 Member

    It does sit for long periods of time as I don’t ride a ton. The petcock appears to be leaking because the paint under and around it is deteriorating. I guess it’s possible some of that got in there, otherwise, the tank and the gas looks pretty clean. There are inline filters before the carburetors. I’m going to replace the petcocks, change the lines and filters, flush the tank and see what happens.

    I really appreciate all the input.
    Paul Sutton and gggGary like this.
  19. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Hey @Mailman think he should scrape paint from the petcock area? :lmao:
  20. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Get a pan under the carbs, open float bowl drains. Run some gas through see what you see.
    Last edited: Oct 17, 2020
    SeaJay likes this.

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