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What would cause my bike to do this?

Discussion in 'Mechanical & Technical' started by smoak, Aug 18, 2012.

  1. Yesterday and Thursday I rode to work on my bike with no issues. However, on the ride home (on both days) my bike slowly lost power and then just died as if it was out of gas even though the tank was at least half full. It would not start again until I let it sit for a few minutes, but eventually it died again while riding it home.

    The bike was running fine in the morning with no apparent issues. It was pretty hot yesterday and Thursday, could the bike have overheated? It is air cooled and I was in slow moving traffic on both days.

    Could a bad battery cause this issue? I don't know how old my battery is, but a few weeks ago I did have to top it off with distilled water and charge it.

    My bike is an 82 Yamaha Maxim XJ650. Does anyone have any ideas?
  2. RedKat600

    RedKat600 Vintage Screwball Staff Member

    Coils overheating and losing spark.....gas boiling in the carb bowls...hard to say without testing it.

  3. I'll put my money on a clogged fuel filter
  4. Or a clogged gas tank vent
  5. shelbyguy

    shelbyguy Picture Whore

    first thoughts
  6. How do I tell if it's clogged? The fuel filter looks about half full of fuel.
  7. If its an in line visual filter just replace cause they r cheap.

    Prob not coil over heating b/c it would take longer than a couple min for it to cool down and even if it did it would over heat very quickly.

    On a bike that old and if it only happens when hot i would think tank not venting.

    It seems your issue is between gas tank and carbs
  8. Ok, it's an inline filter so I'll try replacing it first.
  9. Put in a new fuel filter and it happened again today. It may be a venting issue at this point. :scratchea
  10. I have an '82 X1100, and it has a vacuum actuated valve that allows fuel to flow from the tank when the engine is running. The vacuum from the running engine actuates the valve and allows it to flow fuel.
    The petcocks can be set to four different, on, res, and pri...pri is short for prime which bypasses the vacuum valve (so you can start the engine if it has been sitting a long time and or the carbs have been drained). You can try running the bike with the petcock set to prime and see if the problem goes away. I would caution against leaving the bike sit like that as these old bikes tend to have leaky floats in the carbs...and with no vacuum valve to shut the fuel off you can literally fill your engine with fuel...or worse dump most of your tank out on the garage floor and blow up your garage.
    If yours is similar it could be that the vacuum valve diaphragm has a leak in it and won't stay open. You can buy a rebuild kit cheap off of Ebay.
    Some of the XJ's have the similar vacuum valve built into the petcock itself...and I would imagine they could have similar issues. Again you'd need to rebuild the valve and/or petcock(s).
    By far the best source for this era of Yamaha XJ's is forums. Hard to beat as a source of info for XJ's.
    Hope this helps...
  11. Run it till it dies then open the gas tank filler cap - leaving it open - and then try and restart it - if it fires up OK and seems to run OK then you probably got a clogged tank vent
  12. BTW, the tank vent is in the cap...the tend to get rusty and clog.
  13. james1300

    james1300 Track School Dazed

    Listen when you open it. Sometimes you can hear air entering the take. Like the 'doors' on the starship 'Enterprize'. I'd have said 'sucking' but that would have sent this group into hyperdrive. Gotta watch your back with this crowd!
  14. The petcock can also become clogged, especially if it has a 90 degree bend in it. It happened to me.
  15. But you just said sucking :popcorn:
  16. What is sucking what ???:scratchea
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