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restarting the engine (1982 XJ650 RJ Seca)

Discussion in 'XJ Technical Chat' started by andrewc, Aug 23, 2014.

  1. andrewc

    andrewc Member

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    Let me pick some brains.
    My bike runs awesome since i meticulously rebuilt my carbs.
    Been about 2 years since the rebuild.
    The one thing that I have never really been able to figure out is after running and being shut down again (like stopping for gas) then restarting. It is not just a matter of pushing the button. I have to give the throttle a little twist and wait for the engine to catch up after firing??? Once the revs go up I can chop the throttle and it runs amazing.
    I ran the colortune on it today since I just bought one and it looked good.
    When I first started it it was yellow until the engine caught up to the twist of the throttle. After that the spark was nice and blue.
    The way me thinks is with the throttle open a little the vacuum in the carbs must be less. This would then draw in less fuel right?
    (the carbs are synced by the way)
    I also need to say that it has a 4 to 1 Yoshi exhaust and a high flow filter in the air box and has not been jetted!
    If i increase the jet size on the pilots would this then help by also giving less vacuum in the carbs?
    I should go up sizes on the main jet but this would increase the fuel.
    Any ideas?
    I am quit anal about the way my things run and would like to achieve perfect tuning so I can glote about it. Nothing more satisfying then when somebody comments about how nice your bike sounds and performs for being more then 30 years old.
     
  2. Polock

    Polock Well-Known Member

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    "The way me thinks is with the throttle open a little the vacuum in the carbs must be less. This would then draw in less fuel right?".....right

    some 4 stroke dirt bikes have a "hot start lever" that does the same thing.

    "If i increase the jet size on the pilots would this then help by also giving less vacuum in the carbs? "......no, it won't change the vacuum, just how much fuel the same vacuum draws.

    with the 4/1 and air filter you should up the main jet size. try one size and see how you like it, that shouldn't change the starting though.
    do your plugs look lean?
     
  3. andrewc

    andrewc Member

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    No the plugs look good and after about 2000 km they may almost be a little dark. Thanks for the info. I will try upping the main jet size to see what happens when the snow starts to fly and once again the bike goes into hibernation for yet another winter.
     
  4. PilotSmack

    PilotSmack Active Member

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    I'm thinking float levels. Have you checked em recently?

    And has this problem been continuous since the rebuild, or gotten worse over time?
     
  5. andrewc

    andrewc Member

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    It has always been an issue and the float levels were good after the rebuild but things do change.
     
  6. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Try putting the "choke" (enrichment) on about halfway the next time you encounter that set of circumstances and see what happens. You'll immediately shut it off as soon as the motor starts of course.

    Although it wasn't mentioned, I'm assuming the valve clearances are in spec?
     
  7. andrewc

    andrewc Member

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    I will. Thanks. I will let you know how it goes.
     

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