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Thread: '91 CBR1000F won't rev out

  1. #31
    Join Date
    21st October 2009 - 11:23
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    i had the same sort of problem years ago with an old 750F............chokes were set wrong so they were half on all the time
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  2. #32
    Join Date
    3rd October 2005 - 21:04
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    Thumbs up It seems to work now

    Long story short it seems it was an electrical fault. But in case it wasn't this is what I did before it started working.

    I borrowed a compressor and blew the carbs out to the max. They are very clean. Found one of the vacuum equaliser? hoses (goes between 1-4 and another from 2-3 on the engine side) had a hole so replaced both.
    I also took care to clean not just the main jet, but the tube the needle goes up and down in with a few sprays and air as it looked not perfectly clean (I couldn't really fault it though).
    Disconnected the carbs and fuel pisses out very fast all the way to the carb like it should.
    .....Hooked everything up but no go.

    So in preparation for this possibility I had also borrowed an oscilloscope. And as soon as I attached it the bike worked.
    All traces looked great, no misses. So I put the seat on, drove it and it revved up 3 times ok... and then not again.

    But the bike now had an obvious occasional miss at lower revs, running marginally rougher than normal so I was thinking it was an electrical issue. At the ECU all measurements were in spec and traced ok at one point, so there had to be a dodgy connection somewhere.

    Wiggled the crap out of the ignitiion coil connections (primary side) which I've done before and then found another related connector which plugs the ignition coils into the main wiring loom to the left of the ignition coils. This looked dirty so I cleaned it.

    As soon as I did that the bike revved ok again. Drove it for a few minutes and it keeps working.
    I wouldn't have picked a dodgy connector causing a flat spot but that seems to be what it was

    Thanks for all your help!

  3. #33
    Join Date
    10th May 2006 - 10:37
    Bike
    Aprilia RSV Mille & Aprilia Tuono 660
    Location
    Torbay, North Shore, Akld
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    524
    Good work. Bet you were thanking every god you could think of !
    RSV Mille: No madam, its an Aprilia, not a Harley. If it were a Harley, I would be pushing it !

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