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Testing float height with carbs assembled?

Discussion in 'The Garage' started by XS650D, Jul 21, 2019.

  1. XS650D

    XS650D XS650 Junkie

    Ive been run-in the bike now for approx 3 weeks and run-in great, just when u think u got
    it all fixed something else acts up. Feels like im run-in out of fuel (tank full, carbs clean and set perfect)
    Will start and idle but apply throttle and it pretty much dies. I have great spark on both sides.
    Right side pipe runs cold, think im not getting fuel on right side.Petcock dispenses fuel ok.
    Could it be the float possibly has a hole. I also checked diaphragm and it holds with finger over the
    top hole in the carb mouth. Is there a way on a 77 carb to test what fuel height is without removing
    carb. I have seen some posts on it but confused on how u do on this carb. I have a brass port under
    carb which I assume u connect a clear fuel line to and run up side the carb. but how does the fuel get in there to see level. Thx
    ps: I tried switching spark plug wires side to side as I thought it may be electric issue but no change,
    left side still runs cold. If I run bike it will almost die while riding then suddenly go great then run shit again, no powers think its only run-in on the left cylinder on and off. I swapped the coil, pamco ignition and checked
    timing all good also charging good so no issues there, did not expect any there as ive been thru all that recently.
    gggGary likes this.
  2. XSLeo

    XSLeo XS650 Guru Top Contributor

    Using a clear hose to check fuel level works well. Fuel flows out of the float bowl into the hose. It fills the hose to the same level as the fuel in the float bowl. You need the bike standing up straight for this. The center stand works for this. The fuel in the hose should come up to just below the gasket surface of the float bowl.
    From how you describe the way your bike is running, I don't think it's float level. Sounds more like some crud plugged up your carbs. Time to pull them for a cleaning.
  3. XS650D

    XS650D XS650 Junkie

    There is a brass port at the bottom of each carb (ON FLOAT BOWL) with no cap on it, not sure what that is for.
    Do I connect to that or do I need to get a fitting to replace drain plug that adapts to a piece of clear hose?
    gggGary likes this.
  4. 5twins

    5twins XS650 Guru Top Contributor

    You need a hose fitting for the drain bolt. There's an eBay seller that has this "special tool" all made up. I bought a couple and am very pleased with them. I've used them quite often .....


    A little cheaper route is just to buy the barbed brass fitting and supply your own hose .....


    This tool helped me diagnose a local guy's bike. It ran OK but was very difficult to start. This turned out to be the reason why .....


  5. Gator xs2

    Gator xs2 XS650 Addict

    Just like a water level. Brilliant.
    MaxPete and gggGary like this.
  6. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    Hint ANY bubbles of air in the clear tube destroys the accuracy of the level indication, keep trying til you have a tube that's bubble free.
    MaxPete and Gator xs2 like this.
  7. XS650D

    XS650D XS650 Junkie

    Thats perfect! Thx
    gggGary likes this.
  8. XS650D

    XS650D XS650 Junkie

    Pulled carbs and cleaned main jet and pilot jets, dumped all fuel, checked float height and
    reassembled and still no power, will start and idle ok but apply throttle and it breaks up and falls on its face.
    If I take it for a ride it will run like its about to stall then all off a sudden it goes great.
    I tried turning on choke and applying throttle at same time and it seems to respond well.
    Im stumped. is it possible its could be electrical or will this definitely be fuel related.
    I thought I had all the electrical figured out! Both plugs have spark. But it feels like the right side
    muffler is not getting hot like the left. I never pulled the needle and seats just ran some new fuel thru the
    carb out the bowl drain. Hopeing to flush anything foreign out.
    Thx for any guidance
  9. 5twins

    5twins XS650 Guru Top Contributor

    If turning on the choke makes it better, that seems to indicate a lean condition. Did you check for air leaks? Could be manifolds or shaft seals.
  10. XS650D

    XS650D XS650 Junkie

    k thx 5T will get the starter fluid out.
  11. XS650D

    XS650D XS650 Junkie

    Found problem, clip came off the needle an needle lodge sideways under slide! Tat needle has been in there for 1000,a of miles, I think what happened was the hand made shim I made caught sideways when the slide lifted and popped it off, I reinstalled but doset seem to be runnin rite, maybe the needle got bent or scratched, it looked ok

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