990A overheats right away!

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by dogsdangles, May 21, 2014.

  1. dogsdangles

    dogsdangles Adventurer

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    Jun 14, 2010
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    Seattle, WA
    I've read about the notorious overheating issues with the stock bikes (fans come on too late to cool the engine), but I'm having a different issue: my fans come on when the temperature gauge is at about 50%, and then I start boiling over coolant! This happened to me on a 55 °F day after riding less than two miles on the first ride of the day.

    Any thoughts on this? I'm guessing that perhaps something in the cooling circuit is clogged? Coolant not circulating or something?
    #1
  2. wsmc99

    wsmc99 Been here awhile

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    525
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    SD, CA.
    Radiator cap.
    They fail and do this to the cooling capacity.
    #2
  3. travelsomewhere

    travelsomewhere Been here awhile

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    burp the air from the system too
    #3
  4. Alleycatdad

    Alleycatdad Unbunch yer panties!

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    ^^^This^^^

    SA
    #4
  5. dogsdangles

    dogsdangles Adventurer

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    Thanks, wsmc99, Alleycatdad. I'll take a look at this, but wouldn't I have noticed a coolant leak if the cap had failed? The only coolant leak I had was via the overfull drain on the reservoir when it overheated.
    #5
  6. Alleycatdad

    Alleycatdad Unbunch yer panties!

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    Nope. When the cap fails it allows the coolant to "boil over" into the overflow tank. Btdt.

    SA
    #6
  7. dogsdangles

    dogsdangles Adventurer

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    So I received my shiny new radiator cap, and started the procedure in the manual for bleeding the cooling system. I raised the front of the bike, took off the radiator cap, and unscrewed the bleed screw. Instead of the coolant level in the radiator dropping, as soon as I took out the bleed screw, coolant came spewing out of the radiator cap port!

    Any thoughts on this? I know I need to add fluid to the radiator, but it cannot be filled any more than it already is. I ran the bike for about 5-10 minutes (I should have timed it, but didn't) until 6 temperature bars were illuminated, then I turned the bike off. I'm now waiting for a while for the engine to cool to see if I can add more fluid.

    On the plus side, no coolant came out of the overfill tube this time!
    #7
  8. gefr

    gefr Life is a trip

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    This will allow the air to move from the engine tunnels to the radiator and rad cap, while the bike has the front wheel up high. Squeezing the thick hose at the LHS would also help. Mind the hot coolant overflowing from the rad cap or the bleeder screw.
    Cheers.
    #8
  9. Bighat

    Bighat Adventurer

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    Nov 18, 2013
    Oddometer:
    58
    Had the same thing happened radiator cap was bad need to clean off corrosion where the rubber gasket meets the radiator... Problem solved
    #9
  10. Peanuts

    Peanuts Long timer

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    Even if it appears to be full to the top of the radiator, still burp it before cleaning the seating area on the radiator and fitting the new cap.

    I can do it by myself. With the bike on the centre stand, lift it up by the throttle side handlebar until it balances on the back wheel and the left leg of the centre stand. You can then rock it around the balance point and see the radiator level drop as the trapped air comes out.

    If its a real bad case of trapped air, after removing the radiator cap, loosen the waterpump bleed screw first, let the air come out there, then burp the radiator.
    #10